clk: mxs: add clock support for imx23

Add imx23 clock support based on common clk framework.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
diff --git a/drivers/clk/mxs/Makefile b/drivers/clk/mxs/Makefile
index d9472a8..7086ad3 100644
--- a/drivers/clk/mxs/Makefile
+++ b/drivers/clk/mxs/Makefile
@@ -3,3 +3,5 @@
 #
 
 obj-y += clk.o clk-pll.o clk-ref.o clk-div.o clk-frac.o
+
+obj-$(CONFIG_SOC_IMX23) += clk-imx23.o