[media] s5p-fimc: Iterate for each memory plane

Depth and payload is defined per memory plane. It's better to iterate using
number of memory planes. This was not causing much issue since the rest
of the arrays involved where intialized to zero.

Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>