[infiniband] Generate more specific errors in response to failure MADs

Generate errors within individual MAD transaction consumers such as
ib_pathrec.c and ib_mcast.c, rather than within ib_mi.c.  This allows
for more meaningful error messages to eventually be displayed to the
user.

src/net/infiniband/ib_cm.c

 	size_t private_data_len = 0;
 
 	/* Report failures */
+	if ( ( rc == 0 ) && ( mad->hdr.status != htons ( IB_MGMT_STATUS_OK ) ))
+		rc = -EIO;
 	if ( rc != 0 ) {
 		DBGC ( conn, "CM %p connection request failed: %s\n",
 		       conn, strerror ( rc ) );
 	default:
 		DBGC ( conn, "CM %p unexpected response (attribute %04x)\n",
 		       conn, ntohs ( mad->hdr.attr_id ) );
-		rc = -EIO;
+		rc = -ENOTSUP;
 		break;
 	}
 

src/net/infiniband/ib_mcast.c

 	unsigned long qkey;
 
 	/* Report failures */
+	if ( ( rc == 0 ) && ( mad->hdr.status != htons ( IB_MGMT_STATUS_OK ) ))
+		rc = -ENOTCONN;
 	if ( rc != 0 ) {
 		DBGC ( ibdev, "IBDEV %p QPN %lx join failed: %s\n",
 		       ibdev, qp->qpn, strerror ( rc ) );

src/net/infiniband/ib_mi.c

 	struct ib_mad_hdr *hdr = &mad->hdr;
 	struct ib_mad_transaction *madx;
 	struct ib_mad_agent *agent;
-	int rc;
 
 	/* Look for a matching transaction by TID */
 	list_for_each_entry ( madx, &mi->madx, list ) {
 		if ( memcmp ( &hdr->tid, &madx->mad.hdr.tid,
 			      sizeof ( hdr->tid ) ) != 0 )
 			continue;
-		/* Get transaction result status */
-		rc = ( ( hdr->status == htons ( IB_MGMT_STATUS_OK ) ) ?
-		       0 : -EIO );
 		/* Found a matching transaction */
-		madx->op->complete ( ibdev, mi, madx, rc, mad, av );
+		madx->op->complete ( ibdev, mi, madx, 0, mad, av );
 		return 0;
 	}
 

src/net/infiniband/ib_pathrec.c

 	struct ib_path_record *pathrec = &mad->sa.sa_data.path_record;
 
 	/* Report failures */
+	if ( ( rc == 0 ) && ( mad->hdr.status != htons ( IB_MGMT_STATUS_OK ) ))
+		rc = -ENETUNREACH;
 	if ( rc != 0 ) {
 		DBGC ( ibdev, "IBDEV %p path lookup for %08x:%08x:%08x:%08x "
 		       "failed: %s\n", ibdev, htonl ( dgid->u.dwords[0] ),