clocks: qcom: Add clock enable callback support

Drivers like USB, ethernet etc. uses ".enable" hook to enable clocks.
So add corresponding support for Qcom clock drivers.

Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
diff --git a/arch/arm/mach-snapdragon/clock-apq8096.c b/arch/arm/mach-snapdragon/clock-apq8096.c
index e5011be..6618459 100644
--- a/arch/arm/mach-snapdragon/clock-apq8096.c
+++ b/arch/arm/mach-snapdragon/clock-apq8096.c
@@ -93,3 +93,8 @@
 		return 0;
 	}
 }
+
+int msm_enable(struct clk *clk)
+{
+	return 0;
+}