connman: remove defunkt configuration options

We are carrying support for a couple of configuration options which
are no longer present in connman. Specifically:
; threads: vestigial configuration option needed for defunkt WiMAX plugin
; ntpd: plugin no longer present in connman

Signed-off-by: Simon Dawson <spdawson@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>