clk: mxs: add mxs specific clocks

Add mxs specific clocks, pll, reference clock (PFD), integer divider
and fractional divider.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
diff --git a/drivers/clk/mxs/Makefile b/drivers/clk/mxs/Makefile
new file mode 100644
index 0000000..d9472a8
--- /dev/null
+++ b/drivers/clk/mxs/Makefile
@@ -0,0 +1,5 @@
+#
+# Makefile for mxs specific clk
+#
+
+obj-y += clk.o clk-pll.o clk-ref.o clk-div.o clk-frac.o