ramips: limit 5GHz channels for UniFi 6 Lite

The MT7915 radio currently advertises 2.4GHz channels while the antenna
path only supports 5 GHz. Limit the radio to 5GHz channels to prevent
users from configuring non-supported channels.

Signed-off-by: David Bauer <[email protected]>

target/linux/ramips/dts/mt7621_ubnt_unifi-6-lite.dts

@@ -80,4 +80,5 @@
 &wlan_5g {
 	mediatek,mtd-eeprom = <&factory 0x20000>;
 	mtd-mac-address = <&eeprom 0x6>;
+	ieee80211-freq-limit = <5000000 6000000>;
 };