ARM: ux500: Add placeholder for clk_set_parent

Calling clk_set_parent (e.g. from Ux500 ASoC-driver) generates
build-errors.

Signed-off-by: Ola Lilja <ola.o.lilja@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/arch/arm/mach-ux500/clock.c b/arch/arm/mach-ux500/clock.c
index 7379075..ec35f0a 100644
--- a/arch/arm/mach-ux500/clock.c
+++ b/arch/arm/mach-ux500/clock.c
@@ -223,6 +223,13 @@
 }
 EXPORT_SYMBOL(clk_set_rate);
 
+int clk_set_parent(struct clk *clk, struct clk *parent)
+{
+	/*TODO*/
+	return -ENOSYS;
+}
+EXPORT_SYMBOL(clk_set_parent);
+
 static void clk_prcmu_enable(struct clk *clk)
 {
 	void __iomem *cg_set_reg = __io_address(U8500_PRCMU_BASE)