cpufreq/amd-pstate: Add missing NULL ptr check in amd_pstate_update

Check if policy is NULL before dereferencing it in amd_pstate_update.

Fixes: e8f555d ("cpufreq/amd-pstate: fix setting policy current frequency value")
Signed-off-by: Dhananjay Ugwekar <dhananjay.ugwekar@amd.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Link: https://lore.kernel.org/r/20250205112523.201101-11-dhananjay.ugwekar@amd.com
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>

Author: dhananjay-AMD

drivers/cpufreq/amd-pstate.c

@@ -551,6 +551,9 @@ static void amd_pstate_update(struct amd_cpudata *cpudata, u8 min_perf,
 	struct cpufreq_policy *policy = cpufreq_cpu_get(cpudata->cpu);
 	u8 nominal_perf = READ_ONCE(cpudata->nominal_perf);
 
+	if (!policy)
+		return;
+
 	des_perf = clamp_t(u8, des_perf, min_perf, max_perf);
 
 	policy->cur = perf_to_freq(cpudata, des_perf);