[media] saa7164: fix compiler warning

build/media_build/v4l/saa7164-core.c: In function 'saa7164_initdev':
build/media_build/v4l/saa7164-core.c:1192:6: warning: 'err' may be used uninitialized in this function [-Wmaybe-uninitialized]
  int err, i;
        ^

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>