greybus: connection: generalise CPortFlags handling

Generalise the svc connection-create helper to accept a cport-flags
argument and handle the flags in the connection code instead.

Note that the camera driver currently manages its data connection
directly. We keep E2EFC enabled for now even though it will soon need
to be disabled due to some pending firmware updates.

Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Johan Hovold <johan@hovoldconsulting.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>