driver: be more verbose in driver_handle_method()
driver: be more verbose in driver_handle_method()

Lets add more explanatory comments on what we do in
driver_handle_method(). Also slightly re-order the calls to make them
easier to follow.

Signed-off-by: David Herrmann <fb53b2ddb8d141e0cb39d7c67c2f81b6bc2eb0f7@gmail.com>

bus1/dbus-broker