soc: rockchip: power-domain: check the existing of regmap

Check return value of syscon_node_to_regmap for
rockchip_pm_domain_probe. If err value is returned, probe
procedure should abort.

Signed-off-by: Shawn Lin <[e-mail]>
Signed-off-by: Heiko Stuebner <[e-mail]>

drivers/soc/rockchip/pm_domains.c

···
 	}
 
 	pmu->regmap = syscon_node_to_regmap(parent->of_node);
+	if (IS_ERR(pmu->regmap)) {
+		dev_err(dev, "no regmap available\n");
+		return PTR_ERR(pmu->regmap);
+	}
 
 	/*
 	 * Configure power up and down transition delays for CORE