The v4l2-ioctl core only allows buffer types for which the corresponding
->vidioc_try_fmt_xxx() methods are defined to be used with
vidioc_(q|dq|query)bufs() and vidioc_reqbufs().

This driver only defines ->vidioc_try_fmt_vid_cap() so only VIDEO_CAPTURE
buffers are allowed to be used with cafe_vidioc_reqbufs(),
cafe_vidioc_querybuf(), cafe_vidioc_qbuf(), and cafe_vidioc_dqbuf().

The ->vidioc_(s|g|try|enum)_fmt_vid_cap() methods are only called on
VIDEO_CAPTURE buffers.  Thus, there is no need to check or set the buffer's
'type' field since it must already be set to VIDEO_CAPTURE.  So the
check in cafe_vidioc_enum_fmt_vid_cap() can be removed.

The 'index' field of v4l2_buffer is unsigned so the checks for it being
less than zero can be removed too.
Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>