[media] MAINTAINERS: add a maintainer for s5p-mfc driver

Add a maintainer for s5p-mfc driver.

Signed-off-by: Jeongtae Park <jtp.park@samsung.com>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Kamil Debski <k.debski@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>