IB/core: Fix uninitialized variable use in check_qp_port_pkey_settings

Check the return value from get_pkey_and_subnet_prefix to prevent using
uninitialized variables.

Fixes: d291f1a6 ("IB/core: Enforce PKey security on QPs")
Signed-off-by: Daniel Jurgens <danielj@mellanox.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>

drivers/infiniband/core/security.c

@@ -120,21 +120,25 @@ static int check_qp_port_pkey_settings(struct ib_ports_pkeys *pps,
 		return 0;
 
 	if (pps->main.state != IB_PORT_PKEY_NOT_VALID) {
-		get_pkey_and_subnet_prefix(&pps->main,
+		ret = get_pkey_and_subnet_prefix(&pps->main,
 						 &pkey,
 						 &subnet_prefix);
+		if (ret)
+			return ret;
 
 		ret = enforce_qp_pkey_security(pkey,
 					       subnet_prefix,
 					       sec);
-	}
 		if (ret)
 			return ret;
+	}
 
 	if (pps->alt.state != IB_PORT_PKEY_NOT_VALID) {
-		get_pkey_and_subnet_prefix(&pps->alt,
+		ret = get_pkey_and_subnet_prefix(&pps->alt,
 						 &pkey,
 						 &subnet_prefix);
+		if (ret)
+			return ret;
 
 		ret = enforce_qp_pkey_security(pkey,
 					       subnet_prefix,