parse: const-ify `is_enabled()`
parse: const-ify `is_enabled()`

Signed-off-by: Michael Ira Krufky <00524723a60798c74a43fcc620c25dd7b9ece078@linuxtv.org>

mkrufky/libdvbtee,mkrufky/libdvbtee,mkrufky/libdvbtee,mkrufky/libdvbtee,mkrufky/libdvbtee