[SCSI] aacraid: fib context lock for management ioctls

Alan noticed the lack of locking surrounding the driver's dealings
with the fib context managed by the trio of ioctls that are used by
the RAID management applications to retrieve Adapter Initiated FIBs. I
merely expanded the fib lock to include the fib context. There have
been no field reports of any issues generally because the applications
are relatively static and do not come and go often enough to stress
this area. I bloated this patch a little with some space junk.

Signed-off-by: Mark Salyzyn <aacraid@adaptec.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>