Sync CAM with FreeBSD using lockmgr locks instead of mutexes.

Sync CAM with FreeBSD using lockmgr locks instead of mutexes.
Note:  This is mostly a code sync with FreeBSD which improves stability
in addition to the items listed below.  This provides a framework for
releasing the mplock, but for now it's still there.

Add an xpt_print function to reduce most of the xpt_print_path/printf
pairs. Convert the core code to use it.

Initial cut at Basic Domain Validation.

Make cam_xpt's pronouncements match camcontrol (Tagged -> Command) Queueing.

Pay attention to return value from xpt_bus_register in xpt_init.

Add an xpt_rescan function and a thread that will field rescan requests.
The purpose of this is to allow a SIM (or other entities) to request a bus
rescan and have it then fielded in a different (process) context from the
caller.

Check the return value from cam_periph_acquire.

Drop the periph/sim lock when calling disk_destroy().

Drop the topology lock before calling the periph oninvalidate and dtor
vectors.

For the XPT_SASYNC_CB operation, only decouple the broadcast to the bus
and device lists instead of decoupling the whole operation.  This avoids
problems with SIMs going away.

Split the camisr into per-SIM done queues.  This optimizes the locking a
little bit and allows for direct dispatch of the doneq from certain
contexts that would otherwise face recursive locking problems.

Zero the CCBs when mallocing them.

Only schedule the xpt_finishconfig_task once.

Eliminate the use of M_TEMP.

Add a helper function for registering async callbacks.

Release the bus reference that is acquired when doing a CAMIOCOMMAND ioctl.

Zero scsi_readcapacity allocations so we can really tell if there has
been data returned.

Remove duplicate includes and fix typos.

Add a bunch of definitions and structures to support newer drivers.

When probing a newly found device, don't automatically assume that the
device supports retrieving a serial number.  Instead, first query the
list of VPD pages it does support, and only query the serial number if
it's supported, else silently move on.  This eliminates a lot of noise
during verbose booting, and will likely eliminate the need for most
NOSERIAL quirks.

Reduce diffs from FreeBSD.

Obtained-from: FreeBSD