ARM: timer-sp: add sched_clock support

Add a sched_clock support for the sp804 timer. The clocksource timer
can optionally initialize itself as sched_clock timer.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index a48aecc..4488022 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1127,6 +1127,7 @@
 config ARM_TIMER_SP804
 	bool
 	select CLKSRC_MMIO
+	select HAVE_SCHED_CLOCK
 
 source arch/arm/mm/Kconfig