[nm] Fix the ObjectClass for Set Channel Attribute

In r308 the enum for the object class was fixed and we
started to send the wrong (0x4) instead of the right (0x3)
object class. Fix that.
diff --git a/src/abis_nm.c b/src/abis_nm.c
index 7492636..4f5841a 100644
--- a/src/abis_nm.c
+++ b/src/abis_nm.c
@@ -984,7 +984,7 @@
 
 	oh = (struct abis_om_hdr *) msgb_put(msg, ABIS_OM_FOM_HDR_SIZE);
 	fill_om_fom_hdr(oh, len, NM_MT_SET_CHAN_ATTR,
-			NM_OC_BASEB_TRANSC, bts->bts_nr,
+			NM_OC_CHANNEL, bts->bts_nr,
 			ts->trx->nr, ts->nr);
 	/* FIXME: don't send ARFCN list, hopping sequence, mAIO, ...*/
 	msgb_tlv16_put(msg, NM_ATT_ARFCN_LIST, 1, &arfcn);