libvmmapi: Split the ioctl list into MI and MD lists

libvmmapi: Split the ioctl list into MI and MD lists

To enable use in capability mode, libvmmapi needs a list of all the
ioctls that might be invoked on the vmm device handle.  Some of these
ioctls are amd64-specific.  Move the ioctl list to vmmapi_machdep.c and
define a list of MI ioctls so that the arm64 port can build its own list
without duplicating common ioctls.  No functional change intended.

Reviewed by:	corvink, jhb
MFC after:	2 weeks
Sponsored by:	Innovate UK
Differential Revision:	https://reviews.freebsd.org/D41001