cpufreq/longhaul: handle NULL policy in longhaul_exit

longhaul_exit() was calling cpufreq_cpu_get(0) without checking
for a NULL policy pointer. On some systems, this could lead to a
NULL dereference and a kernel warning or panic.

This patch adds a check using unlikely() and returns early if the
policy is NULL.

Bugzilla: #219962

Signed-off-by: Dennis Beier <nanovim@gmail.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

Author: nanovim

drivers/cpufreq/longhaul.c

@@ -953,6 +953,9 @@ static void __exit longhaul_exit(void)
 	struct cpufreq_policy *policy = cpufreq_cpu_get(0);
 	int i;
 
+	if (unlikely(!policy))
+		return;
+
 	for (i = 0; i < numscales; i++) {
 		if (mults[i] == maxmult) {
 			struct cpufreq_freqs freqs;