fusee: Complete re-write of the hardware initialization code:

- Updated code to match hekate's;
- Improved nxboot (now boots firmwares 2.x successfully);
- Temporarily disabled built-in boot system module support;
- Fixed multiple bugs.

fusee/fusee-primary/src/btn.h

@@ -0,0 +1,12 @@
+#ifndef FUSEE_BTN_H_
+#define FUSEE_BTN_H_
+
+#define BTN_POWER 0x1
+#define BTN_VOL_DOWN 0x2
+#define BTN_VOL_UP 0x4
+
+uint32_t btn_read();
+uint32_t btn_wait();
+uint32_t btn_wait_timeout(uint32_t time_ms, uint32_t mask);
+
+#endif