clk: Skip fetching index for single parent clocks

We don't need to fetch the parent index for clocks if they only
have one parent. Doing this also avoid an unnecessary allocation
for the parent cache.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Michael Turquette <mturquette@linaro.org>

drivers/clk/clk.c

@@ -1390,7 +1390,7 @@ static struct clk *clk_calc_new_rates(struct clk *clk, unsigned long rate)
 	}
 
 	/* try finding the new parent index */
-	if (parent) {
+	if (parent && clk->num_parents > 1) {
 		p_index = clk_fetch_parent_index(clk, parent);
 		if (p_index < 0) {
 			pr_debug("%s: clk %s can not be parent of clk %s\n",