add ipaccess specific attribute set message

Partially apply 9ba65525eaa06a1768aaf35bdee98afcf8026e0a to get
rid of a compile problem. The other part of the mentioned commit
is still in the gprs branch.

Signed-off-by: Holger Hans Peter Freyther <zecke@selfish.org>
diff --git a/openbsc/include/openbsc/abis_nm.h b/openbsc/include/openbsc/abis_nm.h
index a851f82..3e72321 100644
--- a/openbsc/include/openbsc/abis_nm.h
+++ b/openbsc/include/openbsc/abis_nm.h
@@ -229,6 +229,9 @@
 	NM_MT_IPACC_GET_NVATTR		= 0xf2,
 	NM_MT_IPACC_GET_NVATTR_ACK,
 	NM_MT_IPACC_GET_NVATTR_NACK,
+	NM_MT_IPACC_SET_ATTR		= 0xf5,
+	NM_MT_IPACC_SET_ATTR_ACK,
+	NM_MT_IPACC_SET_ATTR_NACK,
 };
 
 enum abis_nm_bs11_cell_alloc {