re-synchronize TSC-s on SMP systems after resume, if necessary

The TSC-s are checked and synchronized only if they were good
originally. That is, invariant, synchronized, etc.

This is necessary on an AMD-based system where after a wakeup from STR I
see that BSP clock differs from AP clocks by a count that roughly
corresponds to one second. The APs are in sync with each other. Not
sure if this is a hardware quirk or a firmware bug.

This is what I see after a resume with this change:

SMP: passed TSC synchronization test after adjustment
acpi_timer0: restoring timecounter, ACPI-fast -> TSC-low

Reviewed by: kib
MFC after: 3 weeks
Differential Revision: https://reviews.freebsd.org/D15551