ARM: mxs: convert platform code to clk_prepare/clk_unprepare

The patch converts mxs platform code to clk_prepare/clk_unprepare
by using helper functions clk_prepare_enable/clk_disable_unprepare.

Signed-off-by: Richard Zhao <richard.zhao@linaro.org>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
diff --git a/arch/arm/mach-mxs/timer.c b/arch/arm/mach-mxs/timer.c
index cace0d2..564a632 100644
--- a/arch/arm/mach-mxs/timer.c
+++ b/arch/arm/mach-mxs/timer.c
@@ -245,7 +245,7 @@
 
 void __init mxs_timer_init(struct clk *timer_clk, int irq)
 {
-	clk_enable(timer_clk);
+	clk_prepare_enable(timer_clk);
 
 	/*
 	 * Initialize timers to a known state