Hyper-V: TLB flush enlightment using hypercall

Currently FreeBSD uses IPI based TLB flushing for remote
TLB flushing. Hyper-V allows hypercalls to flush local and
remote TLB. The use of Hyper-V hypercalls gives significant
performance improvement in TLB operations.

This patch set during test has shown near to 40 percent
TLB performance improvement.

Also this patch adds rep hypercall implementation as well.

Reviewed by: whu, kib
Tested by: whu
Authored-by: Souradeep Chakrabarti <schakrabarti@microsoft.com>
Co-Authored-by: Erni Sri Satya Vennela <ernis@microsoft.com>
MFC after: 1 week
Sponsored by: Microsoft
Differential Revision: https://reviews.freebsd.org/D45521

(cherry picked from commit 2b887687edc25bb4553f0d8a1183f454a85d413d)