Backlight and RGB now working for JJ50 (#2929)

* Added support for JJ50 from KPRepublic, no rgb or backlight control yet. Added as a layout of ymd96 at the moment (same microprocessor). Basic keymap with three layers to get started.

* Added support for JJ50

* Tidied up jj50 code, backlight and RGB is now working.

* Renaming "KEYMAP" to "LAYOUT" to adhere to the new QMK standards.

keyboards/jj50/backlight_custom.h

@@ -0,0 +1,15 @@
+/**
+ * Backlighting code for PS2AVRGB boards (ATMEGA32A)
+ * Kenneth A. (github.com/krusli | krusli.me)
+ */
+
+#ifndef BACKLIGHT_CUSTOM_H
+#define BACKLIGHT_CUSTOM_H
+
+#include <avr/pgmspace.h>
+void b_led_init_ports(void);
+void b_led_set(uint8_t level);
+void b_led_task(void);
+void setPWM(uint16_t xValue);
+
+#endif  // BACKLIGHT_CUSTOM_H