clk: gpio: handle error codes for of_clk_get_parent_count()

We might make bad memory allocations if we get (e.g.) -ENOSYS from
of_clk_get_parent_count().

Noticed by Coverity.

Fixes: f66541ba02 ("clk: gpio: Get parent clk names in of_gpio_clk_setup()")
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Cc: Jyri Sarha <jsarha@ti.com>
Cc: Sergej Sawazki <ce3a@gmx.de>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Michael Turquette <mturquette@baylibre.com>

drivers/clk/clk-gpio.c

@@ -287,12 +287,14 @@ static void __init of_gpio_clk_setup(struct device_node *node,
 	const char **parent_names;
 	int i, num_parents;
 
+	num_parents = of_clk_get_parent_count(node);
+	if (num_parents < 0)
+		return;
+
 	data = kzalloc(sizeof(*data), GFP_KERNEL);
 	if (!data)
 		return;
 
-	num_parents = of_clk_get_parent_count(node);
-
 	parent_names = kcalloc(num_parents, sizeof(char *), GFP_KERNEL);
 	if (!parent_names) {
 		kfree(data);