Fix low power consumption issues

variants/heltec_v4/platformio.ini

@@ -52,6 +52,7 @@ build_flags =
   -D HELTEC_LORA_V4_OLED
   -D PIN_BOARD_SDA=17
   -D PIN_BOARD_SCL=18
+  -D PIN_OLED_RESET=21
   -D ENV_PIN_SDA=4
   -D ENV_PIN_SCL=3
 build_src_filter= ${Heltec_lora32_v4.build_src_filter}