ARM: local timers: Add A15 architected timer support

Add support for the A15 generic timer and clocksource.
As the timer generates interrupts on a different PPI depending
on the execution mode (normal or secure), it is possible to
register two different PPIs.

Change-Id: Ibaddc7f174bc168cef579b66ab06b966878ae155
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Sathish Ambley <sambley@codeaurora.org>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 34ffd9e..3eeac92 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1410,6 +1410,12 @@
 	help
 	  This option enables support for the ARM system coherency unit
 
+config ARM_ARCH_TIMER
+	bool "Architected timer support"
+	select TICK_ONESHOT
+	help
+	  This option enables support for the ARM architected timer
+
 config HAVE_ARM_TWD
 	bool
 	depends on SMP