ath79: fix TP-Link TL-WA901ND v2 PHY stuck in reset

Some newer bootloaders for the TP-Link TL-WA901ND put the ethernet PHY
in reset before loading the kernel, thus the LAN interface is not
working in OpenWrt.

Clear the reset to restore ethernet functionality.

Signed-off-by: David Bauer <mail@david-bauer.net>

target/linux/ath79/dts/ar9132_tplink_tl-wa901nd-v2.dts

@@ -113,6 +113,12 @@
 	phy12: ethernet-phy@c {
 		reg = <0xc>;
 		phy-mode = "mii";
+
+		resets = <&rst 8>;
+		reset-names = "phy";
+
+		reset-assert-us = <10000>;
+		reset-deassert-us = <10000>;
 	};
 };