OP_OSD_Screen: make the rangefinder distance element fixed length

libraries/AP_OSD/AP_OSD_Screen.cpp

@@ -2139,9 +2139,11 @@ void AP_OSD_Screen::draw_rngf(uint8_t x, uint8_t y)
        return;
     }
     if (rangefinder->status_orient(ROTATION_PITCH_270) <= RangeFinder::Status::NoData) {
-        backend->write(x, y, false, "%cNO DATA", SYMBOL(SYM_RNGFD));
+        backend->write(x, y, false, "%c----%c", SYMBOL(SYM_RNGFD), u_icon(DISTANCE));
     } else {
-        backend->write(x, y, false, "%c%2.2f%c", SYMBOL(SYM_RNGFD), u_scale(DISTANCE, (rangefinder->distance_cm_orient(ROTATION_PITCH_270) * 0.01f)), u_icon(DISTANCE));
+        const float distance = rangefinder->distance_cm_orient(ROTATION_PITCH_270) * 0.01f;
+        const char *format = distance < 9.995 ? "%c %1.2f%c" : "%c%2.2f%c";
+        backend->write(x, y, false, format, SYMBOL(SYM_RNGFD), u_scale(DISTANCE, distance), u_icon(DISTANCE));
     }
 }