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>
(cherry picked from commit c00b2df6c8e421ea7aa96f53178dc85db99f2305)

target/linux/ramips/dts/WD03.dts

@@ -102,7 +102,6 @@
 
 &ethernet {
 	mtd-mac-address = <&factory 0x4000>;
-	ralink,port-map = "wllll";
 };
 
 &wmac {