[ipaccess] Add nanoBTS 1900 support

Add support for 1900 nanoBTS by using unified bts_type
GSM_BTS_TYPE_NANOBTS for 900, 1800 and 1900 versions.

Reduce the nanoBTS enum values to one and derive the
version from the user supplied band. In the future we
might want to do auto band detection.

The configuration file needs to be changed to refer
to nanobts instead of nanobts900/nanobts1800.

Signed-off-by: Mike Haben <michael.haben@btinternet.com>
Signed-off-by: Holger Hans Peter Freyther <zecke@selfish.org>
diff --git a/openbsc/src/abis_nm.c b/openbsc/src/abis_nm.c
index 35ed8db..9a2fad7 100755
--- a/openbsc/src/abis_nm.c
+++ b/openbsc/src/abis_nm.c
@@ -1025,8 +1025,7 @@
 	int bts_type = mb->trx->bts->type;
 
 	switch (bts_type) {
-	case GSM_BTS_TYPE_NANOBTS_900:
-	case GSM_BTS_TYPE_NANOBTS_1800:
+	case GSM_BTS_TYPE_NANOBTS:
 		rc = abis_nm_rx_ipacc(mb);
 		break;
 	default: