Revert removal of avrdude make option

keyboards/lets_split/rules.mk

@@ -74,3 +74,15 @@ USE_I2C ?= yes
 SLEEP_LED_ENABLE ?= no    # Breathing sleep LED during USB suspend
 
 CUSTOM_MATRIX = yes
+
+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

keyboards/lets_split/split_util.c

@@ -21,7 +21,7 @@ static void setup_handedness(void) {
   #ifdef EE_HANDS
     isLeftHand = eeprom_read_byte(EECONFIG_HANDEDNESS);
   #else
-    // I2c_MASTER_RIGHT ish deprecate use MASTER_RIGHT instead since this works for both serial and i2c:
+    // I2C_MASTER_RIGHT is deprecated, use MASTER_RIGHT instead, since this works for both serial and i2c
     #if defined(I2C_MASTER_RIGHT) || defined(MASTER_RIGHT)
       isLeftHand = !has_usb();
     #else