fix some scrolling issues

include/ui.h

 #include <stdint.h>
 
 #define KEEP_IN_RANGE(val, min, len) { \
-    while (val > (len - min)) {        \
+    while ((val - min) >= len) {       \
         val -= len;                    \
     }                                  \
     while (val < min) {                \

src/ui.c

 
             // midi only when connected to pc
             if ((tmp == MODE_MIDI) && !usb_is_connected()) {
-                tmp = (tmp + 1) % MACHINE_NUM_MODES;
+                tmp = tmp + val;
+                KEEP_IN_RANGE(tmp, 0, MACHINE_NUM_MODES);
             }
 
             enum machine_modes prev_mode = machine_mode;