Fix Ender 4 / CR-8 compilation

- Assign 243 (like EFB) as Ender-4/CR-8 board ID
- Add to `Makefile`
- Add to `pins.h`

Marlin/Makefile

@@ -149,6 +149,11 @@ else ifeq  ($(HARDWARE_MOTHERBOARD),48)
 HARDWARE_VARIANT ?= arduino
 MCU              ?= atmega2560
 
+# RAMPS equivalent (?) by Creality
+else ifeq  ($(HARDWARE_MOTHERBOARD),243)
+HARDWARE_VARIANT ?= arduino
+MCU              ?= atmega2560
+
 #Gen6
 else ifeq  ($(HARDWARE_MOTHERBOARD),5)
 HARDWARE_VARIANT ?= Gen6