get rid of unnecessary externs

src/reset_save_heap.c

@@ -15,7 +15,7 @@ void sub_81700F8(void)
     imeBackup = REG_IME;
     REG_IME = 0;
     RegisterRamReset(0x00000001);
-    ClearGpuRegBits(REG_OFFSET_DISPCNT, 0x80);
+    ClearGpuRegBits(REG_OFFSET_DISPCNT, DISPCNT_FORCED_BLANK);
     REG_IME = imeBackup;
     gMain.inBattle = FALSE;
     SetSaveBlocksPointers(sub_815355C());