Add SX126X_REGISTER_PATCH for RAK3401

Author: weebl2000

variants/rak3401/platformio.ini

@@ -11,6 +11,7 @@ build_flags = ${nrf52_base.build_flags}
   -D LORA_TX_POWER=22
   -D SX126X_CURRENT_LIMIT=140
   -D SX126X_RX_BOOSTED_GAIN=1
+  -D SX126X_REGISTER_PATCH=1       ; Patch register 0x8B5 for improved RX with SKY66122 FEM
 build_src_filter = ${nrf52_base.build_src_filter}
   +<../variants/rak3401>
   +<helpers/sensors>