[SCSI] be2iscsi: Freeing of WRB and SGL Handle in cleanup task

The WRB and SGL Handle allocated for Login task were not freed
back to the pool after the login process was done. This code
releases the WRB and SGL Handle after the login process.

v2:
- Fix up locking so bh calls are not done when not needed.
- Make beiscsi_cleanup_task static.

Signed-off-by: Jayamohan Kallickal <jayamohan.kallickal@emulex.com>
[various fixes]
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>