media: v4l2-dev.c: Modified the macro SET_VALID_IOCTL

Macros starting with if should be enclosed by a do - while loop
to avoid possible if/else logic defects.
So modified the macro SET_VALID_IOCTL with do - while loop.

[hverkuil: checkpatch: add parenthesis around 'ops']

Signed-off-by: lijian <lijian@yulong.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>