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/clock.c b/arch/arm/mach-mxs/clock.c
index a7093c8..755eec0 100644
--- a/arch/arm/mach-mxs/clock.c
+++ b/arch/arm/mach-mxs/clock.c
@@ -166,7 +166,7 @@
 		return ret;
 
 	if (clk->usecount)
-		clk_enable(parent);
+		clk_prepare_enable(parent);
 
 	mutex_lock(&clocks_mutex);
 	ret = clk->set_parent(clk, parent);