delay bugfix: get_timestamp() off by 2^32 glitch
delay bugfix: get_timestamp() off by 2^32 glitch

When calling delay_get_timestamp() around the same time the 32-bit
counter overflows, a value may be returned that is 2^32 counts too low.
This happened because of a timing issue.

This patch should fix this problem, as validated with > 50h stress
testing.

JitterCompany/mcu_timing