ramips: remove bogus ralink,mtd-eeprom with offset 0x4

ramips: remove bogus ralink,mtd-eeprom with offset 0x4

Several devices in mt76x8 subtarget use the following line to set
up wmac in their DTS(I) files:

ralink,mtd-eeprom = <&factory 0x4>

This is strange for several reasons:
- They should use mediatek,mtd-eeprom on this SOC
- The caldata is supposed to start at 0x0
- The parent DTSI mt7628an.dtsi specifies mediatek,mtd-eeprom anyway,
  starting from 0x0
- The offset coincides with the default location of the MAC address
  in caldata

Based on the comment in b28e94d4bfa1 ("ramips: MiWiFi Nano fixes"),
it looks like the author for this device wanted to actually use
mtd-mac-address instead of ralink,mtd-eeprom. A check on the same
device revealed that actually the MAC address start at offset 4 there,
so the correct caldata offset is 0x0.

Based on these findings, and the fact that the expected location on
this SOC is 0x0, we remove the "ralink,mtd-eeprom = <&factory 0x4>"
statement from all devices in ramips (being only mt7628an anyway).

Thanks to Sungbo Eo for finding and researching this.

Reported-by: Sungbo Eo <mans0n@gorani.run>
Fixes: b28e94d4bfa1 ("ramips: MiWiFi Nano fixes")
Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>