PM / clk: ensure we don't allocate a -ve size of count clks

It is entirely possible for of_count_phandle_wit_args to
return a -ve error return value so we need to check for this
otherwise we end up allocating a negative number of clk objects.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/base/power/clock_ops.c

@@ -159,7 +159,7 @@ int of_pm_clk_add_clks(struct device *dev)
 
 	count = of_count_phandle_with_args(dev->of_node, "clocks",
 					   "#clock-cells");
-	if (count == 0)
+	if (count <= 0)
 		return -ENODEV;
 
 	clks = kcalloc(count, sizeof(*clks), GFP_KERNEL);