PPP, PPPoE: rename PPPOE_TODO to PPPOE_SCNAME_SUPPORT, prepare service name and concentrator support

Rename PPPOE_TODO to PPPOE_SCNAME_SUPPORT because this is the only
feature enclosed by them. Prepare for proper service name and
concentrator name support by moving PPPOE_SCNAME_SUPPORT define to
ppp_opts.h.

Signed-off-by: Sylvain Rochet <gradator@gradator.net>
(cherry picked from commit 96548ede2b)

src/include/netif/ppp/ppp_opts.h

@@ -44,6 +44,13 @@
 #define PPPOE_SUPPORT                   0
 #endif
 
+/**
+ * PPPOE_SCNAME_SUPPORT==1: Enable PPP Over Ethernet Service Name and Concentrator Name support
+ */
+#ifndef PPPOE_SCNAME_SUPPORT
+#define PPPOE_SCNAME_SUPPORT            0
+#endif
+
 /**
  * PPPOL2TP_SUPPORT==1: Enable PPP Over L2TP
  */

src/include/netif/ppp/pppoe.h

@@ -149,10 +149,10 @@ struct pppoe_softc {
   u16_t sc_session;            /* PPPoE session id */
   u8_t sc_state;               /* discovery phase or session connected */
 
-#ifdef PPPOE_TODO
+#if PPPOE_SCNAME_SUPPORT
   u8_t *sc_service_name;       /* if != NULL: requested name of service */
   u8_t *sc_concentrator_name;  /* if != NULL: requested concentrator id */
-#endif /* PPPOE_TODO */
+#endif /* PPPOE_SCNAME_SUPPORT */
   u8_t sc_ac_cookie[PPPOE_MAX_AC_COOKIE_LEN]; /* content of AC cookie we must echo back */
   u8_t sc_ac_cookie_len;       /* length of cookie data */
 #ifdef PPPOE_SERVER