x86: Probe the TSC frequency earlier

This lets us use the TSC to implement early DELAY, limiting the use of
the sometimes-unreliable 8254 PIT.

PR: 262155
Reviewed by: emaste
Tested by: emaste, mike tancsa <mike@sentex.net>, Stefan Hegnauer <stefan.hegnauer@gmx.ch>
Sponsored by: The FreeBSD Foundation

(cherry picked from commit 84369dd52369cbae28970dca20a53d3de1719907)