config: purge obsolete deprecation comment

(Split out from MR !7 (closed))

added against a function in d3fe7f28, left for seemingly no reason in e5fdeda4 when the function it related to was removed

does not apply to the static array which is very much in use

include/vlc_config_cat.h

@@ -191,7 +191,6 @@
 #define ANETWORK_TITLE N_( "Network" )
 #define ANETWORK_HELP N_( "Advanced network settings." )
 
-/* This function is deprecated and is kept only for compatibility */
 static const struct config_category_t categories_array[] =
 {
     /* Interface */