hack: arm64: dts: imx8mq-librem5: add 4G_WAKE as gpio-key
Ideally this (and the ones we describe as leds) line should be handled by a driver I think, but this is a working workaround we do for a long time - on the devkit as well. Describe the 4G_WAKE line (on the modem side mostly called WOWWAN) that gets pulled down (for about 1 second) on incoming call or SMS. At least it should. We see modem devices that don't set this line. So I think it makes sense to add this description now. It eases testing of modems. For example, do: sudo evemu-record and select "gpio-keys" and call the phone from another phone. When it's ringing, it should now print the "KEY_PHONE" key got "pressed".