PPP, PPPoS, moved VJ protocol handler to PPPoS

New callback, netif input, allow low level drivers to extend
ppp_input call, moved PPPoS VJ support to pppos.c.

src/include/netif/ppp/ppp_impl.h

@@ -165,6 +165,8 @@ struct link_callbacks {
   void (*vj_config)(ppp_pcb *pcb, void *ctx, int vjcomp, int cidcomp, int maxcid);
   /* Get and set parameters for the given connection. */
   int (*ioctl)(ppp_pcb *pcb, void *ctx, int cmd, void *arg);
+  /* Pass the processed input packet to the appropriate handler. */
+  err_t (*netif_input)(ppp_pcb *pcb, void *ctx, struct pbuf *p, u16_t protocol);
 };
 
 /*

src/include/netif/ppp/pppos.h

@@ -96,14 +96,5 @@ ppp_pcb *pppos_create(struct netif *pppif, sio_fd_t fd,
 /* PPP over Serial: this is the input function to be called for received data. */
 void pppos_input(ppp_pcb *ppp, u_char* data, int len);
 
-
-/*
- * Functions called from PPP CORE
- *
- * You may use them if you REALLY know what you are doing.
- */
-int pppos_vjc_comp(pppos_pcb *pppos, struct pbuf *pb);
-int pppos_vjc_uncomp(pppos_pcb *pppos, struct pbuf *pb);
-
 #endif /* PPPOS_H */
 #endif /* PPP_SUPPORT && PPPOL2TP_SUPPORT */