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.

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().

Since this driver only defines ->vidioc_try_fmt_vid_cap() the checks can be
removed from vidioc_reqbufs(), vidioc_querybuf(), vidioc_qbuf(), and
vidioc_dqbuf().  Also, the buffer index is unsigned so it's not necessary
to check if it is less than zero.
Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>