add osmo_mi_name(), for MI-to-string like "IMSI-123456"

We have gsm48_mi_to_string() and osmo_bcd2str(), but still lack a function that
conveniently prints both MI type and value in one function call.

Related: http://people.osmocom.org/neels/mi_mi_mi.jpg
Change-Id: I7798c3ef983c2e333b2b9cbffef6f366f370bd81
diff --git a/include/osmocom/gsm/gsm48.h b/include/osmocom/gsm/gsm48.h
index 2b14e6c..0f5727a 100644
--- a/include/osmocom/gsm/gsm48.h
+++ b/include/osmocom/gsm/gsm48.h
@@ -53,6 +53,7 @@
 int gsm48_mi_to_string(char *string, const int str_len,
 			const uint8_t *mi, const int mi_len);
 const char *gsm48_mi_type_name(uint8_t mi);
+const char *osmo_mi_name(const uint8_t *mi, uint8_t mi_len);
 
 /* Parse Routeing Area Identifier */
 void gsm48_parse_ra(struct gprs_ra_id *raid, const uint8_t *buf);