scsi: target/iscsi: fix possible condition with no effect (if == else)

Fix the following warning reported by coccicheck:

drivers/target/iscsi/iscsi_target_nego.c:175:6-8: WARNING: possible
condition with no effect (if == else)

Signed-off-by: Hariprasad Kelam <hariprasad.kelam@gmail.com>
Reviewed-by: David Disseldorp <ddiss@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>