ARM: convert arm/arm64 arch timer to use CLKSRC_OF init

This converts arm and arm64 to use CLKSRC_OF DT based initialization for
the arch timer. A new function arch_timer_arch_init is added to allow for
arch specific setup.

This has a side effect of enabling sched_clock on omap5 and exynos5. There
should not be any reason not to use the arch timers for sched_clock.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Kukjin Kim <kgene.kim@samsung.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Simon Horman <horms@verge.net.au>
Cc: Magnus Damm <magnus.damm@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-samsung-soc@vger.kernel.org
Cc: linux-omap@vger.kernel.org
Cc: linux-sh@vger.kernel.org
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>

arch/arm/mach-vexpress/v2m.c

@@ -1,6 +1,7 @@
 /*
  * Versatile Express V2M Motherboard Support
  */
+#include <linux/clocksource.h>
 #include <linux/device.h>
 #include <linux/amba/bus.h>
 #include <linux/amba/mmci.h>
@@ -23,7 +24,6 @@
 #include <linux/regulator/machine.h>
 #include <linux/vexpress.h>
 
-#include <asm/arch_timer.h>
 #include <asm/mach-types.h>
 #include <asm/sizes.h>
 #include <asm/mach/arch.h>
@@ -446,10 +446,7 @@ static void __init v2m_dt_timer_init(void)
 				irq_of_parse_and_map(node, 0));
 	}
 
-	arch_timer_of_register();
-
-	if (arch_timer_sched_clock_init() != 0)
-		versatile_sched_clock_init(vexpress_get_24mhz_clock_base(),
+	versatile_sched_clock_init(vexpress_get_24mhz_clock_base(),
 				24000000);
 }