media: radio-si476x: drop a container_of() abstraction macro

This isn't used anywhere. So, drop it.
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/radio/radio-si476x.c

@@ -312,12 +312,6 @@ struct si476x_radio {
 	u32 audmode;
 };
 
-static inline struct si476x_radio *
-v4l2_dev_to_radio(struct v4l2_device *d)
-{
-	return container_of(d, struct si476x_radio, v4l2dev);
-}
-
 static inline struct si476x_radio *
 v4l2_ctrl_handler_to_radio(struct v4l2_ctrl_handler *d)
 {