ath79: fix chipidea usb controller detection

Devices with chipidea usb controller does not detect usb hub after
phy-names change to "usb", revert it back to "usb-phy"

Fixes: 787cb9d87e ("ath79: change phy-names to only usb")
Signed-off-by: Simonas Tamošaitis <simsasss@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/18230
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

target/linux/ath79/dts/ar9330.dtsi

@@ -121,7 +121,7 @@
 			interrupts = <3>;
 			resets = <&rst 5>;
 
-			phy-names = "usb";
+			phy-names = "usb-phy";
 			phys = <&usb_phy>;
 
 			status = "disabled";