Add LUN-associated name to VPD, to make Hyper-V Failover Cluster happy.

Sponsored by:	The FreeBSD Foundation
- Modify vm_page_unwire() and vm_page_enqueue() to directly accept
  the queue where to enqueue pages that are going to be unwired.
- Add stronger checks to the enqueue/dequeue for the pagequeues when
  adding and removing pages to them.

Of course, for unmanaged pages the queue parameter of vm_page_unwire() will
be ignored, just as the active parameter today.
This makes adding new pagequeues quicker.

This change effectively modifies the KPI.  __FreeBSD_version will be,
however, bumped just when the full cache of free pages will be
evicted.

Sponsored by:	EMC / Isilon storage division
Reviewed by:	alc
Tested by:	pho