ramips: do not use GPIO function on switch pins on certain devices

ramips: do not use GPIO function on switch pins on certain devices

The pins of the MT7530 switch that translate to GPIO 0, 3, 6, 9 and 12 has
got a function, by default, which does the same thing as the netdev
trigger. Because of bridge offloading on DSA, the netdev trigger won't see
the frames between the switch ports whilst the default function will.

Do not use the GPIO function on switch pins on devices that fall under this
category.

Keep it for:

mt7621_belkin_rt1800.dts: There's only one LED which is for the wan
interface and there's no bridge offloading between the "wan" interface and
other interfaces.

mt7621_yuncore_ax820.dts: There's no bridge offloading between the "wan"
and "lan" interfaces.

Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>