Fix local APIC timer one-shot mode calculation, and mwait configuration parsing

[dbittman]

This patch fixes two things that are broken on non-KVM runs of Twizzler x86_64:

• The calculation for the one-shot APIC timer mode was incorrect, mistakenly adding the current tick value. This resulted in all timing being wrong when not running on KVM.
• Non-kvm qemu emulates the mwait instruction, but seems not to support... anything in it? Fortunately CPUID tells us nothing is supported, so we can check that on startup and fallback to hlt.