drm/amdgpu: Fix null pointer amdgpu_device_fw_loading

Need to check adev->powerplay.pp_funcs.
Signed-off-by: Emily Deng <Emily.Deng@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -1600,7 +1600,7 @@ static int amdgpu_device_fw_loading(struct amdgpu_device *adev)
 		}
 	}
 
-	if (adev->powerplay.pp_funcs->load_firmware) {
+	if (adev->powerplay.pp_funcs && adev->powerplay.pp_funcs->load_firmware) {
 		r = adev->powerplay.pp_funcs->load_firmware(adev->powerplay.pp_handle);
 		if (r) {
 			pr_err("firmware loading failed\n");