[SCSI] be2iscsi: Fix for premature buffer free

This patch fixes a bug where the buffer was being freed as soon as
 submission to HW is done.

Signed-off-by: Jayamohan Kallickal <jayamohank@serverengines.com>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>