[media] s5k6aa: off by one in s5k6aa_enum_frame_interval()

The check is off by one so we could read one space past the end of the
array.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>