[ipaccess] Handle LoadAbort coming from the BTS.

* Be bale to abort the load when the BTS is rejecting the file..
diff --git a/openbsc/src/ipaccess/ipaccess-config.c b/openbsc/src/ipaccess/ipaccess-config.c
index c7d2234..e96b1ab 100644
--- a/openbsc/src/ipaccess/ipaccess-config.c
+++ b/openbsc/src/ipaccess/ipaccess-config.c
@@ -215,6 +215,10 @@
 			printf("Software Download Progress: %d%%\n", percent);
 		percent_old = percent;
 		break;
+	case NM_MT_LOAD_ABORT:
+		fprintf(stderr, "ERROR: Load aborted by the BTS.\n");
+		exit(6);
+		break;
 	}
 	return 0;
 }