vhost: fix guest to host physical address mapping

vhost: fix guest to host physical address mapping

Async copy fails when looking up hpa in the gpa to hpa mapping table.
This happens because the gpa is matched exactly in the merged
mapping table, and the merge loses the mapping entries.
A new range comparison method is introduced to solve this issue.

Fixes: 6563cf92380a ("vhost: fix async copy on multi-page buffers")
Cc: stable@dpdk.org
Signed-off-by: Yuan Wang <yuanx.wang@intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>