Restore queue depth settings across tag disable events. The system often

Restore queue depth settings across tag disable events.  The system often
disables tag queuing temporarily in order to allow controllers a window
to safely perform transfer negotiation with non-compliant devices.  Before
this change, CAM would restore the queue depth to the controller specified
maximum or device quirk level rather than any depth determined by reactions
to QUEUE FULL/BUSY events or an explicit user setting.

During device probe, initialize the flags field for XPT_SCAN_BUS.
The uninitialized value often confused CAM into not bothering to
issue an AC_FOUND_DEVICE async event for new devices.  The reason
this bug wasn't reported earlier is that CAM manually announces
devices after the initial system bus scans.

Obtained-from: FreeBSD