ARM: ep93xx: clockevent support

ARM: ep93xx: clockevent support
I have ported to 3.6-rc2 and slightly modified a previous patch for clockevent support for the ep93xx. The porting mainly consists of sched_clock support + CLKSRC_MMIO usage.
Tested on 9302 based board.

Changes from v1:
* Number of cosmetic style fixes
* Use CLKSRC_MMIO

From: Ahmed Ammar <aammar <at> edge-techno.com>

index e91c7cd..b1d0b11 100644
@@ -451,7 +451,8 @@ config ARCH_EP93XX
 	select CLKDEV_LOOKUP
 	select ARCH_REQUIRE_GPIOLIB
 	select ARCH_HAS_HOLES_MEMORYMODEL
-	select ARCH_USES_GETTIMEOFFSET
+	select GENERIC_CLOCKEVENTS
+	select CLKSRC_MMIO
 	select NEED_MACH_MEMORY_H
 	help
 	  This enables support for the Cirrus EP93xx series of CPUs.