Reduce the timer from 30 ms to 5 ms to fix complaints by libinput about
event processing being too slow:
libinput error: event4 - AT Translated Set 2 keyboard: client bug: event processing lagging behind by 35ms, your system is too slow
With this patch, there is still the problem that not all characters get
picked up when typing fast (issue 36).
Note that before switching lvgl to the release/3.8 branch, it was using
LV_DEF_REFR_PERIOD instead of LV_INDEV_DEF_READ_PERIOD for creating the
lv_indev_read_timer_cb timer.
