[SCSI] libsas: use right function to alloc smp response

In fact the disc_resp buffer will be overwrite by smp response, so we never
found this typo, correct it by using the right one.

Signed-off-by: John Gong <[e-mail]>
Signed-off-by: Jack Wang <[e-mail]>
Signed-off-by: James Bottomley <[e-mail]>

drivers/scsi/libsas/sas_expander.c

···
 	if (!disc_req)
 		return -ENOMEM;
 
-	disc_resp = alloc_smp_req(DISCOVER_RESP_SIZE);
+	disc_resp = alloc_smp_resp(DISCOVER_RESP_SIZE);
 	if (!disc_resp) {
 		kfree(disc_req);
 		return -ENOMEM;