libvmmapi: Make vm_raise_msi() a common function

libvmmapi: Make vm_raise_msi() a common function

Currently, bhyve PCI emulation uses vm_lapic_msi() to raise an MSI in
the guest.  The arm64 port has a similar function, vm_raise_msi().
Add vm_raise_msi() on amd64 as well and have it simply call
vm_lapic_msi() so that bhyve can use a common, generically named
function.

Reviewed by:	corvink, andrew, jhb
MFC after:	2 weeks
Sponsored by:	Innovate UK
Differential Revision:	https://reviews.freebsd.org/D41752