Fix MMU test

buildroot/share/tests/mega2560-tests

 #
 restore_configs
 opt_set LCD_LANGUAGE zh_CN
-opt_set EXTRUDERS 2
+opt_set EXTRUDERS 5
 opt_set NUM_SERVOS 1
 opt_enable ZONESTAR_LCD Z_PROBE_SERVO_NR Z_SERVO_ANGLES DEACTIVATE_SERVOS_AFTER_MOVE BOOT_MARLIN_LOGO_ANIMATED \
            AUTO_BED_LEVELING_3POINT DEBUG_LEVELING_FEATURE EEPROM_SETTINGS EEPROM_CHITCHAT M114_DETAIL \