Add keyboard: mt40 (#2001)

* add keyboard: chinese planck clone

* rename chinese_planck to mt40

* add image for the mt40 board

keyboards/mt40/rules.mk

@@ -0,0 +1,36 @@
+# MCU name
+MCU = atmega32a
+PROTOCOL = VUSB
+
+# unsupported features for now
+NO_UART = yes
+NO_SUSPEND_POWER_DOWN = yes
+
+# processor frequency
+F_CPU = 12000000
+
+# build options
+BOOTMAGIC_ENABLE ?= yes # Virtual DIP switch configuration(+1000)
+MOUSEKEY_ENABLE ?= no   # Mouse keys(+4700)
+EXTRAKEY_ENABLE ?= yes  # Audio control and System control(+450)
+CONSOLE_ENABLE ?= no    # Console for debug(+400)
+COMMAND_ENABLE ?= no    # Commands for debug and configuration
+NKRO_ENABLE ?= no       # Nkey Rollover - if this doesn't work, see here: https://github.com/tmk/tmk_keyboard/wiki/FAQ # nkro-doesnt-work
+BACKLIGHT_ENABLE ?= yes # Enable keyboard backlight functionality
+MIDI_ENABLE ?= no       # MIDI controls
+AUDIO_ENABLE ?= no      # Audio output on port C6
+UNICODE_ENABLE ?= no    # Unicode
+BLUETOOTH_ENABLE ?= no  # Enable Bluetooth with the Adafruit EZ-Key HID
+RGBLIGHT_ENABLE ?= yes  # Enable WS2812 RGB underlight.  Do not enable this with audio at the same time.
+RGBLIGHT_CUSTOM_DRIVER = yes
+TAP_DANCE_ENABLE = no
+
+OPT_DEFS = -DDEBUG_LEVEL=0
+OPT_DEFS += -DBOOTLOADER_SIZE=2048
+
+# custom matrix setup
+CUSTOM_MATRIX = yes
+SRC = matrix.c i2c.c
+
+# programming options
+PROGRAM_CMD = ./keyboards/mt40/program $(TARGET).hex