soc/tegra: pmc: Use of_clk_get_parent_count() instead of open coding

As of_clk_get_parent_count() returns zero on failure, while
of_count_phandle_with_args() might return a negative error code, this
also fixes the issue of possibly using a very big number in the
allocation below.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Jon Hunter <jonathanh@nvidia.com>
Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

drivers/soc/tegra/pmc.c

@@ -31,6 +31,7 @@
 #include <linux/iopoll.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
+#include <linux/of_clk.h>
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
 #include <linux/pm_domain.h>
@@ -725,7 +726,7 @@ static int tegra_powergate_of_get_clks(struct tegra_powergate *pg,
 	unsigned int i, count;
 	int err;
 
-	count = of_count_phandle_with_args(np, "clocks", "#clock-cells");
+	count = of_clk_get_parent_count(np);
 	if (count == 0)
 		return -ENODEV;