Merge Improve Makefile use of avrdude (PR#2477)

Marlin/Makefile

 AVRDUDE_PORT = $(UPLOAD_PORT)
 AVRDUDE_WRITE_FLASH = -Uflash:w:$(BUILD_DIR)/$(TARGET).hex:i
 ifeq ($(shell uname -s), Linux)
-AVRDUDE_CONF = $(ARDUINO_INSTALL_DIR)/hardware/tools/avrdude.conf
+AVRDUDE_CONF = /etc/avrdude/avrdude.conf
 else
 AVRDUDE_CONF = $(ARDUINO_INSTALL_DIR)/hardware/tools/avr/etc/avrdude.conf
 endif
-AVRDUDE_FLAGS = -q -q -D -C$(AVRDUDE_CONF) \
+AVRDUDE_FLAGS = -D -C$(AVRDUDE_CONF) \
 	-p$(MCU) -P$(AVRDUDE_PORT) -c$(AVRDUDE_PROGRAMMER) \
 	-b$(UPLOAD_RATE)