ARM: EXYNOS: Add MFC device tree support

This patch adds device tree entry for MFC v6 in the Exynos5
SoC. Makes the required changes in the clock files and adds
MFC to the DT device list.

Signed-off-by: Naveen Krishna Chatradhi <ch.naveen@samsung.com>
Signed-off-by: Arun Kumar K <arun.kk@samsung.com>
[kgene.kim@samsung.com: fixed section mismatches Seung-Woo Kim reported]
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>