V4L/DVB (5571): V4l1-compat: Make VIDIOCSPICT return errors in a useful way

V4L/DVB (5571): V4l1-compat:  Make VIDIOCSPICT return errors in a useful way

Among other things, VIDIOCSPICT sets the pixel format.  Some drivers
don't support all formats, e.g. cx88 doesn't support the planar formats.
The compat code that translates VIDIOCSPICT into V4L2 ioctls doesn't pass
on any errors, so a userspace program doesn't know if it has selected an
unsupported pixel format.

VIDIOCSPICT sets both the memory capture and overlay formats, and it's
possible that one will be set while the other will fail, e.g. cx88
doesn't even support overlay.  Also, trying to set the overlay format
will fail for non-root users.

Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>