drm/amd/pm: fix the return value of pm message

0 should be right driver return value, 0x1 is the right firmware
return value. So switch to 0 at last.
Signed-off-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Xiaojian Du <xiaojian.du@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c

@@ -152,6 +152,7 @@ int smu_cmn_send_smc_msg_with_param(struct smu_context *smu,
 	if (read_arg)
 		smu_cmn_read_arg(smu, read_arg);
 
+	ret = 0; /* 0 as driver return value */
 out:
 	mutex_unlock(&smu->message_lock);
 	return ret;