media: media/platform: add const to v4l2_file_operations structures

Declare v4l2_file_operations structures as const as they are only stored
in the fops field of video_device structures. This field is of type
const, so declare v4l2_file_operations structures with similar properties
as const.

Cross compiled bfin_capture.o for blackfin arch. vpbe_display.o file did
not cross compile for arm. Could not find any architecture matching the
configuraion symbol for fsl-viu.c file.

Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>
Acked-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>