use nRF Hardware Cryptography. Removes the need for the sdk-nrfxlib submodule

platformio.ini

@@ -130,7 +130,6 @@ build_type = debug ; I'm debugging with ICE a lot now
 build_flags = 
   ${arduino_base.build_flags} -Wno-unused-variable 
   -Isrc/nrf52
-  -Isdk-nrfxlib/crypto/nrf_oberon/include -Lsdk-nrfxlib/crypto/nrf_oberon/lib/cortex-m4/hard-float/ -lliboberon_3.0.7 
 src_filter = 
   ${arduino_base.src_filter} -<esp32/> -<nimble/> -<mesh/wifi/> -<mesh/http/> -<modules/esp32> -<mqtt/>
 lib_ignore =
@@ -142,8 +141,7 @@ build_flags = ${nrf52_base.build_flags}
 lib_deps =
   ${arduino_base.lib_deps}
   ${environmental.lib_deps}
-  Adafruit nRFCrypto
-; https://github.com/Kongduino/Adafruit_nRFCrypto.git
+  https://github.com/Kongduino/Adafruit_nRFCrypto.git
 
 ; Note: By default no lora device is created for this build - it uses a simulated interface
 [env:nrf52840dk]