mgcp_trunk: add value string for trunk type.

Change-Id: I634fb2a03744117e976430468ab5c57d50ab0089
diff --git a/include/osmocom/mgcp/mgcp_trunk.h b/include/osmocom/mgcp/mgcp_trunk.h
index c62f731..326b16a 100644
--- a/include/osmocom/mgcp/mgcp_trunk.h
+++ b/include/osmocom/mgcp/mgcp_trunk.h
@@ -13,6 +13,10 @@
 	MGCP_TRUNK_E1,
 };
 
+extern const struct value_string mgcp_trunk_type_strs[];
+static inline const char *mgcp_trunk_type_strs_str(enum mgcp_trunk_type val)
+{ return get_value_string(mgcp_trunk_type_strs, val); }
+
 struct mgcp_trunk {
 	struct llist_head entry;
 
diff --git a/src/libosmo-mgcp/mgcp_trunk.c b/src/libosmo-mgcp/mgcp_trunk.c
index 8ff6f6a..5c9a888 100644
--- a/src/libosmo-mgcp/mgcp_trunk.c
+++ b/src/libosmo-mgcp/mgcp_trunk.c
@@ -28,6 +28,12 @@
 #include <osmocom/mgcp/mgcp_e1.h>
 #include <osmocom/abis/e1_input.h>
 
+const struct value_string mgcp_trunk_type_strs[] = {
+	{ MGCP_TRUNK_VIRTUAL,		"virtual" },
+	{ MGCP_TRUNK_E1,		"e1" },
+	{ 0, NULL }
+};
+
 /*! allocate trunk and add it (if required) to the trunk list.
  *  (called once at startup by VTY).
  *  \param[in] cfg mgcp configuration.