ARM: S5PV210: Add EPLL clock operations

This patch adds EPLL specific clock get_rate/set_rate operations
on S5PV210.

Signed-off-by: Seungwhan Youn <sw.youn@samsung.com>
Acked-by: Jassi Brar <jassi.brar@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>