system/physmem: handle hugetlb correctly in qemu_ram_remap()

system/physmem: handle hugetlb correctly in qemu_ram_remap()

The list of hwpoison pages used to remap the memory on reset
is based on the backend real page size.
To correctly handle hugetlb, we must mmap(MAP_FIXED) a complete
hugetlb page; hugetlb pages cannot be partially mapped.

Signed-off-by: William Roche <william.roche@oracle.com>
Co-developed-by: David Hildenbrand <david@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/20250211212707.302391-2-william.roche@oracle.com
Signed-off-by: Peter Xu <peterx@redhat.com>