opp: Fix error check in dev_pm_opp_attach_genpd()

dev_pm_domain_attach_by_name() may return NULL in some cases,
so IS_ERR() doesn't meet the requirements. Thus fix it.

Fixes: 6319aee1 ("opp: Attach genpds to devices from within OPP core")
Signed-off-by: Tang Bin <tangbin@cmss.chinamobile.com>
[ Viresh: Replace ENODATA with ENODEV ]
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

drivers/opp/core.c

@@ -2528,8 +2528,8 @@ struct opp_table *dev_pm_opp_attach_genpd(struct device *dev,
 		}
 
 		virt_dev = dev_pm_domain_attach_by_name(dev, *name);
-		if (IS_ERR(virt_dev)) {
-			ret = PTR_ERR(virt_dev);
+		if (IS_ERR_OR_NULL(virt_dev)) {
+			ret = PTR_ERR(virt_dev) ? : -ENODEV;
 			dev_err(dev, "Couldn't attach to pm_domain: %d\n", ret);
 			goto err;
 		}