KVM: Detect Extended Destination ID support

KVM advertises support for the Extended Destination ID standard via
bit 15 of the value returned in the EAX register when KVM features
are queried via CPUID.

Tested on: EC2 r8i.96xlarge
MFC after: 3 weeks
Sponsored by: Amazon
Differential Revision: https://reviews.freebsd.org/D55427