[media] streamzap: Fix a compilation warning when compiled builtin

drivers/media/rc/streamzap.c: In function ‘streamzap_probe’:
drivers/media/rc/streamzap.c:460:2: warning: statement with no effect

Cc: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>