Fix "Loop done in xxx ms" when time is updated in the loop

[jdavid]

one more thing, i notice this `1554717665.400 INFO Loop done in 400 ms`
it gives the wrong Loop time
...maybe only when reading GPS?
could that be related?
...ahh Gps updates RTC and resets millis, therfore the wrong loop time. (edited) 

[jdavid]

Fixed with commit 0c25e7ae