ARM: spear: add __init to spear_clocksource_init()

I get a build warning because spear_clocksource_init() calls
clocksource_mmio_init(), but it doesn't have an __init annotation.
Fix that.
Signed-off-by: Alex Elder <elder@linaro.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/arm/mach-spear/time.c

@@ -71,7 +71,7 @@ static void clockevent_set_mode(enum clock_event_mode mode,
 static int clockevent_next_event(unsigned long evt,
 				 struct clock_event_device *clk_event_dev);
 
-static void spear_clocksource_init(void)
+static void __init spear_clocksource_init(void)
 {
 	u32 tick_rate;
 	u16 val;