ARM: pm-imx5: add clk_prepare/clk_unprepare

It's for migrating to generic clk framework API.

Signed-off-by: Richard Zhao <richard.zhao@linaro.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
diff --git a/arch/arm/mach-imx/pm-imx5.c b/arch/arm/mach-imx/pm-imx5.c
index 6dc0934..e26a9cb 100644
--- a/arch/arm/mach-imx/pm-imx5.c
+++ b/arch/arm/mach-imx/pm-imx5.c
@@ -89,7 +89,7 @@
 
 static int mx5_suspend_prepare(void)
 {
-	return clk_enable(gpc_dvfs_clk);
+	return clk_prepare_enable(gpc_dvfs_clk);
 }
 
 static int mx5_suspend_enter(suspend_state_t state)
@@ -119,7 +119,7 @@
 
 static void mx5_suspend_finish(void)
 {
-	clk_disable(gpc_dvfs_clk);
+	clk_disable_unprepare(gpc_dvfs_clk);
 }
 
 static int mx5_pm_valid(suspend_state_t state)