moved eap_from_string() fomr libcharon to libstrongswan to make it available in starter

src/libstrongswan/credentials/auth_cfg.h

@@ -81,6 +81,14 @@ extern enum_name_t *eap_type_names;
  */
 extern enum_name_t *eap_type_short_names;
 
+/**
+ * Lookup the EAP method type from a string.
+ *
+ * @param name		EAP method name (such as "md5", "aka")
+ * @return			method type, 0 if unkown
+ */
+eap_type_t eap_type_from_string(char *name);
+
 /**
  * Authentication config to use during authentication process.
  *