drm/amdgpu: sw pstate switch should only be for vega20

Driver steered p-state switching is designed for Vega20 only.
Also simplify early return for temporary disable due to SMU FW
bug.
Signed-off-by: Jonathan Kim <Jonathan.Kim@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.c

@@ -395,7 +395,9 @@ int amdgpu_xgmi_set_pstate(struct amdgpu_device *adev, int pstate)
 	bool init_low = hive->pstate == AMDGPU_XGMI_PSTATE_UNKNOWN;
 
 	/* fw bug so temporarily disable pstate switching */
-	if (!hive || adev->asic_type == CHIP_VEGA20)
+	return 0;
+
+	if (!hive || adev->asic_type != CHIP_VEGA20)
 		return 0;
 
 	mutex_lock(&hive->hive_lock);