V4L/DVB (9171): S2API: Stop an OOPS if illegal commands are dumped in S2API.

Quick fix to stop an OOPS if illegal commands are dumped in S2API.

Signed-off-by: Darron Broad <darron@kewl.org>
Signed-off-by: Steven Toth <stoth@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>