Denote warnings in demuxer that can happen in normal situations

(cherry picked from commit f6287174)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/demux/mod.c

@@ -149,7 +149,7 @@ static int Open( vlc_object_t *p_this )
 
         if( Validate( p_demux, psz_ext ) )
         {
-            msg_Warn( p_demux, "MOD validation failed (ext=%s)", psz_ext ? psz_ext : "");
+            msg_Dbg( p_demux, "MOD validation failed (ext=%s)", psz_ext ? psz_ext : "");
             return VLC_EGENERIC;
         }
     }

modules/demux/ts.c

@@ -555,7 +555,7 @@ static int DetectPacketSize( demux_t *p_demux )
         msg_Warn( p_demux, "this does not look like a TS stream, continuing" );
         return TS_PACKET_SIZE_188;
     }
-    msg_Warn( p_demux, "TS module discarded (lost sync)" );
+    msg_Dbg( p_demux, "TS module discarded (lost sync)" );
     return -1;
 }