cpufreq/amd-pstate: Disable preferred cores on designs with workload classification

On designs that have workload classification, it's preferred that
the amd-hfi driver is used to provide hints to the scheduler of
which cores to use instead of the amd-pstate driver.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Reviewed-by: Perry Yuan <perry.yuan@amd.com>
Acked-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/20250609200518.3616080-11-superm1@kernel.org

Author: superm1

drivers/cpufreq/amd-pstate.c

@@ -826,6 +826,13 @@ static void amd_pstate_init_prefcore(struct amd_cpudata *cpudata)
 	if (!amd_pstate_prefcore)
 		return;
 
+	/* should use amd-hfi instead */
+	if (cpu_feature_enabled(X86_FEATURE_AMD_WORKLOAD_CLASS) &&
+	    IS_ENABLED(CONFIG_AMD_HFI)) {
+		amd_pstate_prefcore = false;
+		return;
+	}
+
 	cpudata->hw_prefcore = true;
 
 	/* Priorities must be initialized before ITMT support can be toggled on. */