set a reset pin if RESET_PIN is defined in variant.h (#212)

* set a reset pin if RESET_PIN is defined in variant.h

* move setting of reset pin to wiring.c

* remove leftover code

cores/nRF5/wiring.c

@@ -44,6 +44,21 @@ void init( void )
   NRF_RTC1->INTENSET = RTC_INTENSET_OVRFLW_Msk;
   NRF_RTC1->EVTENSET = RTC_EVTEN_OVRFLW_Msk;
   NRF_RTC1->TASKS_START = 1;
+
+  #if defined(RESET_PIN)
+  if (((NRF_UICR->PSELRESET[0] & UICR_PSELRESET_CONNECT_Msk) != (UICR_PSELRESET_CONNECT_Connected << UICR_PSELRESET_CONNECT_Pos)) ||
+      ((NRF_UICR->PSELRESET[1] & UICR_PSELRESET_CONNECT_Msk) != (UICR_PSELRESET_CONNECT_Connected << UICR_PSELRESET_CONNECT_Pos))){
+      NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Wen << NVMC_CONFIG_WEN_Pos;
+      while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}
+      NRF_UICR->PSELRESET[0] = RESET_PIN;
+      while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}
+      NRF_UICR->PSELRESET[1] = RESET_PIN;
+      while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}
+      NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Ren << NVMC_CONFIG_WEN_Pos;
+      while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}
+      NVIC_SystemReset();
+  }
+  #endif
 }
 
 #ifdef __cplusplus