Remove T5S3, T-Echo, CardKB and nRF support

examples/simple_sensor/main.cpp

@@ -71,7 +71,7 @@ void setup() {
   fast_rng.begin(radio_get_rng_seed());
 
   FILESYSTEM* fs;
-#if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
+#if defined(STM32_PLATFORM)
   InternalFS.begin();
   fs = &InternalFS;
   IdentityStore store(InternalFS, "");