net: designware: avoid regulator enable failure

Use regulator_set_enable_if_allowed() to avoid failure if regulator is
shared between multiple devices.

Signed-off-by: Ben Wolsieffer <ben.wolsieffer@hefring.com>

drivers/net/designware.c

diff --git a/drivers/net/designware.c b/drivers/net/designware.c
index 7ecedc3..2fd92cf 100644
--- a/drivers/net/designware.c
+++ b/drivers/net/designware.c
@@ -894,7 +894,7 @@
 	if (ret) {
 		debug("%s: No phy supply\n", dev->name);
 	} else {
-		ret = regulator_set_enable(phy_supply, true);
+		ret = regulator_set_enable_if_allowed(phy_supply, true);
 		if (ret) {
 			puts("Error enabling phy supply\n");
 			return ret;