[Keyboard] Add support for jj4x4 numpad/macropad by Kprepublic (#5016)

* added keyboard jj4x4, a shorter version of the jj40

* removed useless file

* edited jj4x4 readme.md

* optimized array size in jj4x4 config.h, removed reference to jj40 layouts from rules.mk

* removed custom matrix for this ps2avrgb board, refactored column and row pins

keyboards/jj4x4/i2c.h

@@ -0,0 +1,25 @@
+/*
+Copyright 2016 Luiz Ribeiro <luizribeiro@gmail.com>
+
+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/>.
+*/
+
+#ifndef __I2C_H__
+#define __I2C_H__
+
+void i2c_init(void);
+void i2c_set_bitrate(uint16_t bitrate_khz);
+uint8_t i2c_send(uint8_t address, uint8_t *data, uint16_t length);
+
+#endif