Add rule for flashing microcontroller using avrdude

keyboards/handwired/magicforce68/rules.mk

@@ -70,4 +70,14 @@ ifndef QUANTUM_DIR
 	include ../../../Makefile
 endif
 
+avrdude: build
+	ls /dev/tty* > /tmp/1; \
+	echo "Reset your Pro Micro now"; \
+	while [[ -z $$USB ]]; do \
+	  sleep 1; \
+	  ls /dev/tty* > /tmp/2; \
+	  USB=`diff /tmp/1 /tmp/2 | grep -o '/dev/tty.*'`; \
+	done; \
+	avrdude -p $(MCU) -c avr109 -P $$USB -U flash:w:$(BUILD_DIR)/$(TARGET).hex
 
+.PHONY: avrdude