combo-layer: fix default "update" mode
When the "history" option is not set in the combo-layer.conf, the
intended default was to use the traditional method. Passing "True" as
default when querying the config was unintentional.
Also remove some left-over debugging code.
Signed-off-by: Patrick Ohly <patrick.ohly@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>