Instead of passing FatFS structs around, unmount; other changes

fusee/fusee-secondary/src/splash_screen.h

@@ -1,9 +1,11 @@
 #ifndef FUSEE_SPLASH_SCREEN_H
 #define FUSEE_SPLASH_SCREEN_H
 
+#include <stdint.h>
+
 /* TODO: Actually make this a real thing. */
 extern unsigned char g_default_splash_screen[1];
 
 void display_splash_screen_bmp(const char *custom_splash_path);
 
-#endif
+#endif