ARM: S5P6442: Add clock support for S5P6442

This patch adds clock support for S5P6442. This patch adds the clock
register definitions and the various system clocks in S5P6442.

Signed-off-by: Adityapratap Sharma <aditya.ps@samsung.com>
Signed-off-by: Atul Dahiya <atul.dahiya@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>