mmc: host: omap_hsmmc: use devm_regulator_get_optional() for vmmc

Since vmmc can be optional for some platforms, use
devm_regulator_get_optional() for vmmc. Now return error only
if the return value of devm_regulator_get_optional() is not the
same as -ENODEV, since with -EPROBE_DEFER, the regulator can be
obtained later and all other errors are fatal.
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/omap_hsmmc.c

@@ -345,15 +345,19 @@ static int omap_hsmmc_reg_get(struct omap_hsmmc_host *host)
 {
 	struct regulator *reg;
 	int ocr_value = 0;
+	int ret;
 
 	if (mmc_pdata(host)->set_power)
 		return 0;
 
-	reg = devm_regulator_get(host->dev, "vmmc");
+	reg = devm_regulator_get_optional(host->dev, "vmmc");
 	if (IS_ERR(reg)) {
-		dev_err(host->dev, "unable to get vmmc regulator %ld\n",
+		ret = PTR_ERR(reg);
+		if (ret != -ENODEV)
+			return ret;
+		host->vcc = NULL;
+		dev_dbg(host->dev, "unable to get vmmc regulator %ld\n",
 			PTR_ERR(reg));
-		return PTR_ERR(reg);
 	} else {
 		host->vcc = reg;
 		ocr_value = mmc_regulator_get_ocrmask(reg);