media: vicodec: check type in g/s_selection

Check that the selection buf_type is valid before calling get_q_data() to
avoid hitting the WARN(1) in that function if the buffer type is not valid.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reported-by:  <syzbot+44b24cff6bf96006ecfa@syzkaller.appspotmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>