[SCSI] aacraid: fib context lock for management ioctls (take 2)

The first patch (a119ee8e) was a bit
too aggressive and nested the locks (!) unit testing was in
error. This patch was reverted by
203a512f.

This new patch should fix the locks correctly.

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