[Keyboard] Add meishi2 keyboard (#6138)

* Add meishi2

* Fix pin assign

* Fix matrix representation macro

* Remove needless mcu conf

keyboards/meishi2/keymaps/default/config.h

@@ -0,0 +1,19 @@
+/* Copyright 2019 Biacco42
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+// place overrides here