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-at91/at91rm9200_time.c

@@ -274,8 +274,3 @@ void __init at91rm9200_timer_init(void)
 	/* register clocksource */
 	clocksource_register_hz(&clk32k, AT91_SLOW_CLOCK);
 }
-
-struct sys_timer at91rm9200_timer = {
-	.init		= at91rm9200_timer_init,
-};
-