bgpd: remove stream_pnt use for notify data

* bgp_packet.c: (bgp_open_receive) Remove the stream_pnt introduced
  in c69698704806a9ac50. stream_pnt / BGP_INPUT_PNT / etc. should be avoided
  as much possible, and I/O put through the lib/stream checked buffer as much
  as possible.

  Not really any functional effect here given the fixed size, other than to
  remove something that shouldn't be copied.

bgpd/bgp_packet.c

@@ -1314,7 +1314,6 @@ bgp_open_receive (struct peer *peer, bgp_size_t size)
   int mp_capability;
   u_int8_t notify_data_remote_as[2];
   u_int8_t notify_data_remote_id[4];
-  u_int16_t *holdtime_ptr;
 
   realpeer = NULL;
   
@@ -1322,7 +1321,6 @@ bgp_open_receive (struct peer *peer, bgp_size_t size)
   version = stream_getc (peer->ibuf);
   memcpy (notify_data_remote_as, stream_pnt (peer->ibuf), 2);
   remote_as  = stream_getw (peer->ibuf);
-  holdtime_ptr = (u_int16_t *)stream_pnt (peer->ibuf);
   holdtime = stream_getw (peer->ibuf);
   memcpy (notify_data_remote_id, stream_pnt (peer->ibuf), 4);
   remote_id.s_addr = stream_get_ipv4 (peer->ibuf);
@@ -1628,10 +1626,11 @@ bgp_open_receive (struct peer *peer, bgp_size_t size)
 
   if (holdtime < 3 && holdtime != 0)
     {
+      uint16_t netholdtime = htons (holdtime);
       bgp_notify_send_with_data (peer,
 		                 BGP_NOTIFY_OPEN_ERR,
 		                 BGP_NOTIFY_OPEN_UNACEP_HOLDTIME,
-                                 (u_int8_t *)holdtime_ptr, 2);
+                                 (u_int8_t *) &netholdtime, 2);
       return -1;
     }