ramips: drop non-existant ralink,port-map for Ravpower WD03

The property "ralink,port-map" has been obsolete long before
this device was added, and the device is a one-port anyway.
Just remove it.

Fixes: 5ef79af4f8 ("ramips: add support for Ravpower WD03")

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>

target/linux/ramips/dts/mt7620n_ravpower_wd03.dts

@@ -100,7 +100,6 @@
 
 &ethernet {
 	mtd-mac-address = <&factory 0x4000>;
-	ralink,port-map = "wllll";
 };
 
 &wmac {