clk: propagate round_rate for CLK_SET_RATE_PARENT case

Need to propagate round_rate call for the clk that has no .round_rate
operation but with flag CLK_SET_RATE_PARENT set.

For example, clk_mux is a clk with no .round_rate operation.  However,
it could likely be in a clk_set_rate propagation path, saying it has
parent clk who has .round_rate and .set_rate operations.
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>

drivers/clk/clk.c

@@ -587,8 +587,12 @@ unsigned long __clk_round_rate(struct clk *clk, unsigned long rate)
 	if (!clk)
 		return -EINVAL;
 
-	if (!clk->ops->round_rate)
+	if (!clk->ops->round_rate) {
+		if (clk->flags & CLK_SET_RATE_PARENT)
+			return __clk_round_rate(clk->parent, rate);
+		else
 			return clk->rate;
+	}
 
 	if (clk->parent)
 		parent_rate = clk->parent->rate;