Use the new vb2_queue_change_type() function in .vidioc_reqbufs and
.vidioc_create_bufs instead of changing the queue type manually in
vidioc_s_fmt_vbi_cap() and vidioc_s_fmt_sliced_vbi_cap().

This allows for a more consistent behavior, as .vidioc_reqbufs and
.vidioc_create_bufs are when the queue will become "busy".
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>