greybus: connection: Create gb_connection_create_range() to specify hd-cport-id range

We need to allocate specific hd-cport-id for AP's control/svc protocols.
Support that by splitting functionality of gb_connection_create() into a
new routine, which takes range of hd_cport_id's to allocate from.

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