[media] hdpvr: hide unused variable

The i2c client pointer is only used when CONFIG_I2C is set, and
otherwise produces a compile-time warning:

drivers/media/usb/hdpvr/hdpvr-core.c: In function 'hdpvr_probe':
drivers/media/usb/hdpvr/hdpvr-core.c:276:21: error: unused variable 'client' [-Werror=unused-variable]

This uses the same #ifdef to hide the variable when the code using
it is hidden.

Signed-off-by: Arnd Bergmann <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/usb/hdpvr/hdpvr-core.c

···
 	struct hdpvr_device *dev;
 	struct usb_host_interface *iface_desc;
 	struct usb_endpoint_descriptor *endpoint;
+#if IS_ENABLED(CONFIG_I2C)
 	struct i2c_client *client;
+#endif
 	size_t buffer_size;
 	int i;
 	int retval = -ENOMEM;