move 麦田 boards into /mt (#16095)

Co-authored-by: Nick Brassel <nick@tzarc.org>

keyboards/mt/split75/config.h

@@ -0,0 +1,21 @@
+#pragma once
+
+#define VENDOR_ID       0x594D
+#define PRODUCT_ID      0x0001
+#define DEVICE_VER      0x0001
+#define MANUFACTURER    YMDK
+#define PRODUCT         Split75
+
+/* matrix size */
+#define MATRIX_ROWS 8
+#define MATRIX_COLS 14
+
+#define LED_NUM_LOCK_PIN D0
+#define LED_CAPS_LOCK_PIN D1
+#define LED_SCROLL_LOCK_PIN D6
+
+#define RGBLED_NUM 8
+#define RGBLIGHT_ANIMATIONS
+#define RGBLIGHT_SLEEP
+
+#define BACKLIGHT_PIN D4