remove a 'sleep' in control_finish

remove a 'sleep' in control_finish.
it may case process blocked under heavy traffic?

it seems coming from 0.70, but no comment at all. not sure about the usage.

QUOTE:

https://github.com/xelerance/xl2tpd/commit/ce2515775cecaedc26eef65c30c7eb2153af6982

Michael Richardson
2005-11-21 version from sourceforge's CVS

0.70
--
Change path for config files from /etc/l2tp to /etc/l2tpd (jacco2@dds.nl)
Turn of echo no ptys to pppd (Damien de Soto)
Add pty name to command line passed to pppd (Chris Wilson)
Added listen-addr parameter to l2tpd.conf (jacco2@dds.nl)
Close stdin when in daemon mode (jacco2@dds.nl)
Improve interoperability with MSL2TP (jacco2@dds.nl)
Eliminate some warnings (jacco2@dds.nl)