[SCSI] qla4xxx: fix up residual handling

the check in the residual case has an incorrect test of scsi_status
(the logic is reversed, it should be scsi_status != 0 instead of
!scsi_status.  Since we checked a few lines above that scsi_status was
non-zero, just eliminate this test
Signed-off-by: David C Somayajulu <david.somayajulu@qlogic.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

drivers/scsi/qla4xxx/ql4_isr.c

@@ -100,8 +100,7 @@ static void qla4xxx_status_entry(struct scsi_qla_host *ha,
 
 		if (sts_entry->iscsiFlags &ISCSI_FLAG_RESIDUAL_UNDER) {
 			scsi_set_resid(cmd, residual);
-			if (!scsi_status && ((scsi_bufflen(cmd) - residual) <
-				cmd->underflow)) {
+			if ((scsi_bufflen(cmd) - residual) < cmd->underflow) {
 
 				cmd->result = DID_ERROR << 16;