[media] s5p-mfc: Remove dead conditional code

CONFIG_PM is always enabled on Exynos platforms, so remove dead code
related to early development of MFC driver on platform without PM support.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>