media: flexcop-i2c: Constify struct i2c_algorithm

'struct i2c_algorithm' is not modified in this driver.

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

On a x86_64, with allmodconfig, as an example:
Before:
======
text data bss dec hex filename
6645 216 16 6877 1add drivers/media/common/b2c2/flexcop-i2c.o

After:
=====
text data bss dec hex filename
6721 160 16 6897 1af1 drivers/media/common/b2c2/flexcop-i2c.o

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

drivers/media/common/b2c2/flexcop-i2c.c

···
 	return I2C_FUNC_I2C;
 }
 
-static struct i2c_algorithm flexcop_algo = {
+static const struct i2c_algorithm flexcop_algo = {
 	.master_xfer	= flexcop_master_xfer,
 	.functionality	= flexcop_i2c_func,
 };