Bump DVBsub priority above avcodec

Since now avcodec module accepts dvbsub, it is always taken, even if it
fails to decode...

Close #10655

modules/codec/dvbsub.c

@@ -119,7 +119,7 @@ vlc_module_begin ()
 #   define DVBSUB_CFG_PREFIX "dvbsub-"
     set_description( N_("DVB subtitles decoder") )
     set_shortname( N_("DVB subtitles") )
-    set_capability( "decoder", 50 )
+    set_capability( "decoder", 80 )
     set_category( CAT_INPUT )
     set_subcategory( SUBCAT_INPUT_SCODEC )
     set_callbacks( Open, Close )