[sw_load] For the nanoBTS just open the firmware

* The two version strings are not in an easy to parse header
  and from my trace it appears like the whole file is sent
  to the BTS. So just open the firmware file..
diff --git a/openbsc/src/abis_nm.c b/openbsc/src/abis_nm.c
index bb7248b..64b87b5 100644
--- a/openbsc/src/abis_nm.c
+++ b/openbsc/src/abis_nm.c
@@ -1372,6 +1372,17 @@
 		/* rewind to start of file */
 		rewind(sw->stream);
 		break;	
+	case GSM_BTS_TYPE_NANOBTS:
+		sw->stream = fdopen(sw->fd, "r");
+		if (!sw->stream) {
+			perror("fdopen");
+			return -1;
+		}
+
+		/* TODO: extract that from the filename or content */
+		sw->file_id_len = 0;
+		sw->file_version_len = 0;
+		break;
 	default:
 		/* We don't know how to treat them yet */
 		close(sw->fd);