PPP, remove useless ppp_init function

Simon says:

ppp_init() does not seem to be used. The only thing it does is calling
magic_init(), which is not required because it its called again later
from ppp_input().

Also, the time from startup is rather constant, so calling sys_jiffies()
from ppp_init() does not create a random number.

src/core/init.c

@@ -59,7 +59,6 @@
 #include "lwip/nd6.h"
 #include "lwip/mld6.h"
 #include "lwip/api.h"
-#include "netif/ppp/ppp_impl.h"
 
 /* Compile-time sanity checks for configuration errors.
  * These can be done independently of LWIP_DEBUG, without penalty.
@@ -345,9 +344,6 @@ lwip_init(void)
 #if LWIP_DNS
   dns_init();
 #endif /* LWIP_DNS */
-#if PPP_SUPPORT
-  ppp_init();
-#endif
 
 #if LWIP_TIMERS
   sys_timeouts_init();

src/include/netif/ppp/ppp_impl.h

@@ -378,13 +378,6 @@ struct pppd_stats {
  * PPP private functions
  */
 
-/*
- * Functions called from lwIP core.
- */
-
-/* initialize the PPP subsystem */
-int ppp_init(void);
-
 
 /*
  * Functions called from PPP link protocols.

src/netif/ppp/ppp.c

@@ -561,18 +561,6 @@ err:
 /*** PRIVATE FUNCTION DEFINITIONS ***/
 /************************************/
 
-/* Initialize the PPP subsystem. */
-int ppp_init(void) {
-
-    /*
-     * Initialize magic number generator now so that protocols may
-     * use magic numbers in initialization.
-     */
-    magic_init();
-
-    return 0;
-}
-
 /*
  * Create a new PPP control block.
  *