target/pscsi: blk_make_request() returns an ERR_PTR()

The check is wrong here because blk_make_request() returns an
ERR_PTR() and it doesn't return NULL.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NNicholas A. Bellinger <nab@linux-iscsi.org>

drivers/target/target_core_pscsi.c

@@ -1091,7 +1091,7 @@ static int pscsi_do_task(struct se_task *task)
 
 		req = blk_make_request(pdv->pdv_sd->request_queue, hbio,
 				       GFP_KERNEL);
-		if (!req) {
+		if (IS_ERR(req)) {
 			pr_err("pSCSI: blk_make_request() failed\n");
 			goto fail;
 		}