abis_nm: Introduce abis_nm_dump_foh()

This is a more modern way of printing the Abis OML Formatted Object
Header, without assuming that it would be used in a log statement
or prescribing the log level to be used.

Change-Id: I9b2c2afec28882b817d104d5b062651ade7aadd8
diff --git a/include/osmocom/gsm/abis_nm.h b/include/osmocom/gsm/abis_nm.h
index dd7ba0d..823b5a4 100644
--- a/include/osmocom/gsm/abis_nm.h
+++ b/include/osmocom/gsm/abis_nm.h
@@ -41,16 +41,14 @@
 extern const struct tlv_definition abis_nm_osmo_att_tlvdef;
 extern const struct tlv_definition abis_nm_att_tlvdef_ipa;
 
+const char *abis_nm_dump_foh(const struct abis_om_fom_hdr *foh);
+
 /*! write a human-readable OML header to the debug log
  *  \param[in] ss Logging sub-system
  *  \param[in] foh A-bis OML FOM header
  */
 #define abis_nm_debugp_foh(ss, foh)					    \
-	DEBUGP(ss, "OC=%s(%02x) INST=(%02x,%02x,%02x) ",		    \
-		get_value_string(abis_nm_obj_class_names, (foh)->obj_class),  \
-		(foh)->obj_class, (foh)->obj_inst.bts_nr, (foh)->obj_inst.trx_nr, \
-		(foh)->obj_inst.ts_nr)
-
+	DEBUGP(ss, "%s ", abis_nm_dump_foh(foh))
 
 int abis_nm_chcomb4pchan(enum gsm_phys_chan_config pchan);
 enum gsm_phys_chan_config abis_nm_pchan4chcomb(uint8_t chcomb);