media: dvb-usb-v2: Constify struct i2c_algorithm

'struct i2c_algorithm' are not modified in these drivers.

Constifying this structure moves some data to a read-only section, so
increase overall security, especially when the structure holds some
function pointers.

More over, dvb_usb_device_properties->i2c_algo seems to only be copied in
i2c_adapter->algo, which is already a "const struct i2c_algorithm".
This is done in dvb_usbv2_i2c_init()

On a x86_64, with allmodconfig, as an example:
Before:
======
text data bss dec hex filename
35366 5832 36 41234 a112 drivers/media/usb/dvb-usb-v2/af9015.o

After:
=====
text data bss dec hex filename
35430 5768 36 41234 a112 drivers/media/usb/dvb-usb-v2/af9015.o

Signed-off-by: Christophe JAILLET <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>

drivers/media/usb/dvb-usb-v2/af9015.c

···
 	return I2C_FUNC_I2C;
 }
 
-static struct i2c_algorithm af9015_i2c_algo = {
+static const struct i2c_algorithm af9015_i2c_algo = {
 	.master_xfer = af9015_i2c_xfer,
 	.functionality = af9015_i2c_func,
 };

drivers/media/usb/dvb-usb-v2/af9035.c

···
 	return I2C_FUNC_I2C;
 }
 
-static struct i2c_algorithm af9035_i2c_algo = {
+static const struct i2c_algorithm af9035_i2c_algo = {
 	.master_xfer = af9035_i2c_master_xfer,
 	.functionality = af9035_i2c_functionality,
 };

drivers/media/usb/dvb-usb-v2/anysee.c

···
 	return I2C_FUNC_I2C;
 }
 
-static struct i2c_algorithm anysee_i2c_algo = {
+static const struct i2c_algorithm anysee_i2c_algo = {
 	.master_xfer   = anysee_master_xfer,
 	.functionality = anysee_i2c_func,
 };

drivers/media/usb/dvb-usb-v2/au6610.c

···
 	return I2C_FUNC_I2C;
 }
 
-static struct i2c_algorithm au6610_i2c_algo = {
+static const struct i2c_algorithm au6610_i2c_algo = {
 	.master_xfer   = au6610_i2c_xfer,
 	.functionality = au6610_i2c_func,
 };

drivers/media/usb/dvb-usb-v2/az6007.c

···
 	return I2C_FUNC_I2C;
 }
 
-static struct i2c_algorithm az6007_i2c_algo = {
+static const struct i2c_algorithm az6007_i2c_algo = {
 	.master_xfer = az6007_i2c_xfer,
 	.functionality = az6007_i2c_func,
 };

drivers/media/usb/dvb-usb-v2/ce6230.c

···
 	return I2C_FUNC_I2C;
 }
 
-static struct i2c_algorithm ce6230_i2c_algorithm = {
+static const struct i2c_algorithm ce6230_i2c_algorithm = {
 	.master_xfer   = ce6230_i2c_master_xfer,
 	.functionality = ce6230_i2c_functionality,
 };

drivers/media/usb/dvb-usb-v2/dvb_usb.h

···
 	int (*download_firmware) (struct dvb_usb_device *,
 			const struct firmware *);
 
-	struct i2c_algorithm *i2c_algo;
+	const struct i2c_algorithm *i2c_algo;
 
 	unsigned int num_adapters;
 	int (*get_adapter_count) (struct dvb_usb_device *);

drivers/media/usb/dvb-usb-v2/dvbsky.c

···
 	return I2C_FUNC_I2C;
 }
 
-static struct i2c_algorithm dvbsky_i2c_algo = {
+static const struct i2c_algorithm dvbsky_i2c_algo = {
 	.master_xfer   = dvbsky_i2c_xfer,
 	.functionality = dvbsky_i2c_func,
 };

drivers/media/usb/dvb-usb-v2/ec168.c

···
 	return I2C_FUNC_I2C;
 }
 
-static struct i2c_algorithm ec168_i2c_algo = {
+static const struct i2c_algorithm ec168_i2c_algo = {
 	.master_xfer   = ec168_i2c_xfer,
 	.functionality = ec168_i2c_func,
 };

drivers/media/usb/dvb-usb-v2/gl861.c

···
 	return I2C_FUNC_I2C;
 }
 
-static struct i2c_algorithm gl861_i2c_algo = {
+static const struct i2c_algorithm gl861_i2c_algo = {
 	.master_xfer   = gl861_i2c_master_xfer,
 	.functionality = gl861_i2c_functionality,
 };

drivers/media/usb/dvb-usb-v2/lmedm04.c

···
 	return I2C_FUNC_I2C;
 }
 
-static struct i2c_algorithm lme2510_i2c_algo = {
+static const struct i2c_algorithm lme2510_i2c_algo = {
 	.master_xfer   = lme2510_i2c_xfer,
 	.functionality = lme2510_i2c_func,
 };

drivers/media/usb/dvb-usb-v2/mxl111sf.c

···
 	return I2C_FUNC_I2C;
 }
 
-static struct i2c_algorithm mxl111sf_i2c_algo = {
+static const struct i2c_algorithm mxl111sf_i2c_algo = {
 	.master_xfer   = mxl111sf_i2c_xfer,
 	.functionality = mxl111sf_i2c_func,
 #ifdef NEED_ALGO_CONTROL

drivers/media/usb/dvb-usb-v2/rtl28xxu.c

···
 	return I2C_FUNC_I2C;
 }
 
-static struct i2c_algorithm rtl28xxu_i2c_algo = {
+static const struct i2c_algorithm rtl28xxu_i2c_algo = {
 	.master_xfer   = rtl28xxu_i2c_xfer,
 	.functionality = rtl28xxu_i2c_func,
 };