x86: Do not attempt to calibrate the LAPIC timer if no APIC is present

Reported and tested by: Michael Butler <imb@protected-networks.net>
Reviewed by: jhb, kib
Fixes: 62d09b46ad75 ("x86: Defer LAPIC calibration until after timecounters are available")
Sponsored by: The FreeBSD Foundation

(cherry picked from commit 0ecda8d5ae896b229f13bfe73ffa3a7fc81cc550)