utils: reimplement NM_UTILS_ENUM2STR_DEFINE() without helper function

The compiler might be able to optimize the switch better.
But more importantly, it has the type information of the enum
and can give warnings about unmentioned enum values.

src/NetworkManagerUtils.c

@@ -1880,45 +1880,6 @@ nm_utils_flags2str (const NMUtilsFlags2StrDesc *descs,
 
 /*****************************************************************************/
 
-const char *
-nm_utils_enum2str (const NMUtilsEnum2StrDesc *descs,
-                   gsize n_descs,
-                   int val,
-                   char *buf,
-                   gsize len)
-{
-	gsize i;
-
-#if NM_MORE_ASSERTS > 10
-	nm_assert (descs);
-	nm_assert (n_descs > 0);
-	for (i = 0; i < n_descs; i++) {
-		gsize j;
-
-		nm_assert (descs[i].name && descs[i].name[0]);
-		for (j = 0; j < i; j++)
-			nm_assert (descs[j].value != descs[i].value);
-	}
-#endif
-
-	nm_utils_to_string_buffer_init (&buf, &len);
-
-	if (!len)
-		return buf;
-
-	for (i = 0; i < n_descs; i++) {
-		if (val == descs[i].value) {
-			g_strlcpy (buf, descs[i].name, len);
-			return buf;
-		}
-	}
-
-	g_snprintf (buf, len, "(%d)", val);
-	return buf;
-};
-
-/*****************************************************************************/
-
 /**
  * nm_utils_get_shared_wifi_permission:
  * @connection: the NMConnection to lookup the permission.