move rak to nrf52_core, remove nrf52840_core

platformio.ini

@@ -77,14 +77,6 @@ build_flags = ${arduino_base.build_flags}
   -D NRF52_PLATFORM
   -D LFS_NO_ASSERT=1
 
-[nrf52840_base]
-extends = nrf52_base
-build_flags = ${nrf52_base.build_flags}
-lib_deps =
-  ${nrf52_base.lib_deps}
-  rweather/Crypto @ ^0.4.0
-  https://github.com/adafruit/Adafruit_nRF52_Arduino
-
 ; ----------------- RP2040 ---------------------
 
 [rp2040_base]