usb: dwc2: Use regulator_set_enable_if_allowed

With the commit 4fcba5d556b4 ("regulator: implement basic reference
counter") the return value of regulator_set_enable may be EALREADY or
EBUSY for fixed/gpio regulators.

Change to use the more relaxed regulator_set_enable_if_allowed to
continue if regulator already was enabled or disabled.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>  # rockpro64-rk3399
Reviewed-by: Marek Vasut <marex@denx.de>
diff --git a/drivers/usb/host/dwc2.c b/drivers/usb/host/dwc2.c
index 9818f9b..637eb2d 100644
--- a/drivers/usb/host/dwc2.c
+++ b/drivers/usb/host/dwc2.c
@@ -194,8 +194,8 @@
 		return 0;
 	}
 
-	ret = regulator_set_enable(priv->vbus_supply, true);
-	if (ret) {
+	ret = regulator_set_enable_if_allowed(priv->vbus_supply, true);
+	if (ret && ret != -ENOSYS) {
 		dev_err(dev, "Error enabling vbus supply\n");
 		return ret;
 	}
@@ -208,12 +208,10 @@
 	struct dwc2_priv *priv = dev_get_priv(dev);
 	int ret;
 
-	if (priv->vbus_supply) {
-		ret = regulator_set_enable(priv->vbus_supply, false);
-		if (ret) {
-			dev_err(dev, "Error disabling vbus supply\n");
-			return ret;
-		}
+	ret = regulator_set_enable_if_allowed(priv->vbus_supply, false);
+	if (ret && ret != -ENOSYS) {
+		dev_err(dev, "Error disabling vbus supply\n");
+		return ret;
 	}
 
 	return 0;