Call XenIfaceCleanup from IRP_MJ_CLEANUP

Call XenIfaceCleanup from IRP_MJ_CLEANUP

XenIfaceCleanup was not called which meant that some watches, event
channels and grant entries were not cleaned up on closing the device
handle and required explicit cleanup. Add a IRP handler to call
XenIfaceCleanup from the IRP_MJ_CLEANUP for a specific FileObject.
This ensures all watches, event channels and grant entries are
destroyed in the event of the caller crashing or not gracefullly
cleaning up objects.

Signed-off-by: Owen Smith <owen.smith@citrix.com>