5045 use atomic_{inc,dec}_* instead of atomic_add_*

@@ -371,11 +371,11 @@
                 if (vid != 0) {
                         flow_desc.fd_vid = vid;
                         flow_desc.fd_mask |= FLOW_LINK_VID;
                 }
 
-                grp->mbg_id = atomic_add_32_nv(&mac_bcast_id, 1);
+                grp->mbg_id = atomic_inc_32_nv(&mac_bcast_id);
                 (void) sprintf(flow_name,
                     "mac/%s/mcast%d", mip->mi_name, grp->mbg_id);
 
                 rc = mac_flow_create(&flow_desc, NULL, flow_name,
                     grp, FLOW_MCAST, &grp->mbg_flow_ent);