ARM: tegra: add clk_prepare/clk_unprepare

Use clk_prepare/clk_unprepare as required by the generic clk framework.

Tested on Ventana and Cardhu.

Signed-off-by: Prashant Gaikwad <pgaikwad@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
diff --git a/arch/arm/mach-tegra/powergate.c b/arch/arm/mach-tegra/powergate.c
index f5b12fb..15d5065 100644
--- a/arch/arm/mach-tegra/powergate.c
+++ b/arch/arm/mach-tegra/powergate.c
@@ -146,7 +146,7 @@
 	if (ret)
 		goto err_power;
 
-	ret = clk_enable(clk);
+	ret = clk_prepare_enable(clk);
 	if (ret)
 		goto err_clk;
 
@@ -162,7 +162,7 @@
 	return 0;
 
 err_clamp:
-	clk_disable(clk);
+	clk_disable_unprepare(clk);
 err_clk:
 	tegra_powergate_power_off(id);
 err_power: