scd: Remove --debug-disable-ticker option.

* scd/scdaemon.c (ticker_disabled): Remove.
(handle_tick, need_tick): Remove.
(handle_connections): Don't check ticker_disabled.

Now, removal of device/card is only done by the function
scd_update_reader_status_file, it should be called if needed.

• Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>