Merge pull request #1092 from liquidraver/rakgps

Fix RAK4631 GPS UART pin macros for L76K to work

Author: ripplebiz

variants/rak4631/platformio.ini

@@ -9,8 +9,8 @@ build_flags = ${nrf52_base.build_flags}
   -D RAK_BOARD
   -D PIN_BOARD_SCL=14
   -D PIN_BOARD_SDA=13
-  -D PIN_GPS_TX=16
-  -D PIN_GPS_RX=15
+  -D PIN_GPS_TX=PIN_SERIAL1_RX
+  -D PIN_GPS_RX=PIN_SERIAL1_TX
   -D PIN_GPS_EN=-1
   -D PIN_OLED_RESET=-1
   -D RADIO_CLASS=CustomSX1262