ARM: EXYNOS4: Implement kernel timers using MCT

ARM: EXYNOS4: Implement kernel timers using MCT

The Multi-Core Timer(MCT) of EXYNOS4 is designed for implementing
clock source timer and clock event timers. This patch implements
1 clock source timer with 64 bit free running counter of MCT and
2 clock event timers with two of 31-bit tick counters.

Signed-off-by: Changhwan Youn <chaos.youn@samsung.com>
Cc: Ben Dooks <ben-linux@fluff.org>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>