access/satip: add missing initialization of sys->tcp_sock

As the object referred to by sys is allocated with calloc,
sys->tcp_sock will be equal to 0 if an error occurs prior to it being
assigned a value in satip_open (such as when encountering a malformed
URI).

This will cause the error clean-up to assume that tcp->tcp_sock refers
to an open file-descriptor, triggering an assert if no suck
file-descriptor exists or closing a fd that access/satip definitely
should not mess with.

fixes: #18344
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/access/satip.c

@@ -636,6 +636,7 @@ static int satip_open(vlc_object_t *obj)
 
     sys->udp_sock = -1;
     sys->rtcp_sock = -1;
+    sys->tcp_sock = -1;
 
     /* convert url to lowercase, some famous m3u playlists for satip contain
      * uppercase parameters while most (all?) satip servers do only understand