ARM: delete struct sys_timer

Now that the only field in struct sys_timer is .init, delete the struct,
and replace the machine descriptor .timer field with the initialization
function itself.

This will enable moving timer drivers into drivers/clocksource without
having to place a public prototype of each struct sys_timer object into
include/linux; the intent is to create a single of_clocksource_init()
function that determines which timer driver to initialize by scanning
the device dtree, much like the proposed irqchip_init() at:
http://www.spinics.net/lists/arm-kernel/msg203686.html

Includes mach-omap2 fixes from Igor Grinberg.

Tested-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Stephen Warren <swarren@nvidia.com>

arch/arm/mach-exynos/common.h

@@ -12,7 +12,7 @@
 #ifndef __ARCH_ARM_MACH_EXYNOS_COMMON_H
 #define __ARCH_ARM_MACH_EXYNOS_COMMON_H
 
-extern struct sys_timer exynos4_timer;
+extern void exynos4_timer_init(void);
 
 struct map_desc;
 void exynos_init_io(struct map_desc *mach_desc, int size);