Add edvorakjp keymap for the Helix (rev2) keyboard (#3340)

* add readme.md

* add extern declaration of edvorakjp_config to edvorakjp.h

* add oled.c

* add layout definitions

* add keymap.c

* add rules.mk

* fix rgblight issue: rgblight_setrgb() ignore RGBLIGHT_LIMIT_VAL

keyboards/helix/rev2/keymaps/edvorakjp/oled.h

@@ -0,0 +1,19 @@
+#ifndef OLED_USER_H
+#define OLED_USER_H
+
+//SSD1306 OLED update loop, make sure to add #define SSD1306OLED in config.h
+#include "ssd1306.h"
+#include "edvorakjp.h"
+
+//assign the right code to your layers for OLED display
+#define L_BASE 0
+
+extern uint8_t is_master;
+extern bool japanese_mode;
+
+void matrix_update(struct CharacterMatrix *dest,
+                   const struct CharacterMatrix *source);
+void render_status(struct CharacterMatrix *matrix);
+void iota_gfx_task_user(void);
+
+#endif // OLED_CONFIG_USER_H