clk: composite: Export clk_hw_register_composite()

Export clk_hw_register_composite() to support user built as module.

ERROR: modpost: "clk_hw_register_composite" [drivers/clk/imx/mxc-clk.ko]
undefined!
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Reviewed-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

drivers/clk/clk-composite.c

@@ -328,6 +328,7 @@ struct clk_hw *clk_hw_register_composite(struct device *dev, const char *name,
 					   rate_hw, rate_ops, gate_hw,
 					   gate_ops, flags);
 }
+EXPORT_SYMBOL_GPL(clk_hw_register_composite);
 
 struct clk_hw *clk_hw_register_composite_pdata(struct device *dev,
 			const char *name,