[PATCH v2 2/4] mountmgr: Add support for IRP_MJ_QUERY_VOLUME_INFORMATION.

[Erich E. Hoover]

This patch allows the mountmgr to handle the volume information
request IRP, allowing volume information to be queried from the
mountmgr.

v2: Per Zeb's request, now storing the volume with the disk_device so
that the lookup doesn't require a search.

Best,
Erich