Disable MIDI on preonic to fix firmware compilation errors

keyboards/preonic/rules.mk

@@ -61,7 +61,7 @@ CONSOLE_ENABLE = yes         # 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 = yes            # MIDI controls
+MIDI_ENABLE = no            # MIDI controls
 AUDIO_ENABLE = yes           # Audio output on port C6
 UNICODE_ENABLE = no         # Unicode
 BLUETOOTH_ENABLE = no       # Enable Bluetooth with the Adafruit EZ-Key HID