firmware: arm_scmi: pm: Propagate return value to caller

of_genpd_add_provider_onecell may return error, so let's propagate
its return value to caller

Link: https://lore.kernel.org/r/20211116064227.20571-1-peng.fan@oss.nxp.com
Fixes: 898216c9 ("firmware: arm_scmi: add device power domain support using genpd")
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

drivers/firmware/arm_scmi/scmi_pm_domain.c

@@ -138,9 +138,7 @@ static int scmi_pm_domain_probe(struct scmi_device *sdev)
 	scmi_pd_data->domains = domains;
 	scmi_pd_data->num_domains = num_domains;
 
-	of_genpd_add_provider_onecell(np, scmi_pd_data);
-
-	return 0;
+	return of_genpd_add_provider_onecell(np, scmi_pd_data);
 }
 
 static const struct scmi_device_id scmi_id_table[] = {