x86/svm: Use physical addresses for HSA and Host VMCB

x86/svm: Use physical addresses for HSA and Host VMCB

They are only referenced by physical address (either the HSA MSR, or via
VMSAVE/VMLOAD which take a physical operand).  Allocating xenheap pages and
storing their virtual address is wasteful.

Allocate them with domheap pages instead, taking the opportunity to suitably
NUMA-position them.  This avoids Xen needing to perform a virt to phys
translation on every context switch.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>