media: v4l: common: Remove v4l2_find_nearest_format

v4l2_find_nearest_format is not useful for drivers in finding the best
matching format as it assumes a V4L2 specific struct. Drivers will use
v4l2_find_nearest_size instead.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>