V4L/DVB (11271): usbvision: Remove buffer type checks from enum_fmt_vid_cap, XXXbuf

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)buf() and vidioc_reqbufs().

Since this driver only defines ->vidioc_try_fmt_vid_cap() the checks can be
removed from vidioc_reqbufs(), vidioc_qbuf(), and 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 setting the
buffer type in vidioc_enum_fmt_vid_cap() can be removed.

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