cpufreq: armada-37xx: stop using 0 as NULL pointer

stable inclusion
from stable-v5.10.166
commit 00f23016118781f85d7ffda2dccf9a43de6f1c98
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7TH9O

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=00f23016118781f85d7ffda2dccf9a43de6f1c98

--------------------------------

[ Upstream commit 08f0adb1 ]

Use NULL for NULL pointer to fix the following sparse warning:
drivers/cpufreq/armada-37xx-cpufreq.c:448:32: sparse: warning: Using plain integer as NULL pointer
Signed-off-by: NMiles Chen <miles.chen@mediatek.com>
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: Nsanglipeng <sanglipeng1@jd.com>

drivers/cpufreq/armada-37xx-cpufreq.c

@@ -443,7 +443,7 @@ static int __init armada37xx_cpufreq_driver_init(void)
 		return -ENODEV;
 	}
 
-	clk = clk_get(cpu_dev, 0);
+	clk = clk_get(cpu_dev, NULL);
 	if (IS_ERR(clk)) {
 		dev_err(cpu_dev, "Cannot get clock for CPU0\n");
 		return PTR_ERR(clk);