usb: ehci-mx6: 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.

Based on 335799b7252a ("usb: dwc2: Use regulator_set_enable_if_allowed")

Signed-off-by: Marek Vasut <[e-mail]>
Reviewed-by: Fabio Estevam <[e-mail]>
Reviewed-by: Mattijs Korpershoek <[e-mail]>

drivers/usb/host/ehci-mx6.c

···
 #if CONFIG_IS_ENABLED(DM_REGULATOR)
 	if (priv->vbus_supply) {
 		int ret;
-		ret = regulator_set_enable(priv->vbus_supply,
-					   (type == USB_INIT_DEVICE) ?
-					   false : true);
+		ret = regulator_set_enable_if_allowed(priv->vbus_supply,
+						      (type == USB_INIT_DEVICE) ?
+						      false : true);
 		if (ret && ret != -ENOSYS) {
 			printf("Error enabling VBUS supply (ret=%i)\n", ret);
 			return ret;