g/s_parm should fill in readbuffers.
For non-webcams s_parm should return -ENOTTY instead of -EINVAL.
Signed-off-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NDevin Heitmueller <dheitmueller@kernellabs.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>