Trigger timeout truncated to 8 bit (pxarCore)

[piberger]

The value for trigger timeout in clocks which is passed here:
https://github.com/psi46/pxar/blob/master/core/hal/hal.cc#L211
is a uint8_t, which leads to truncated events marked as PKAM and unwanted resets for events with ~40 or more hits.
It should be 16 bit instead.