* refactor: rtc_clock now defined by variants/*/target modules

variants/lilygo_tlora_v2_1/target.h

@@ -5,9 +5,11 @@
 #include <helpers/RadioLibWrappers.h>
 #include <helpers/LilyGoTLoraBoard.h>
 #include <helpers/CustomSX1276Wrapper.h>
+#include <helpers/AutoDiscoverRTCClock.h>
 
 extern LilyGoTLoraBoard board;
 extern WRAPPER_CLASS radio_driver;
+extern AutoDiscoverRTCClock rtc_clock;
 
 bool radio_init();
 uint32_t radio_get_rng_seed();