greybus: connection: call connection_init hook after setting the handler

greybus: connection: call connection_init hook after setting the handler

In gb_connection_init() we set the connection_handler for each supported
protocol, but we never call the connection_init hook after doing so. This
results in a failure being returned so fix it by calling the connection_init
hook to get a good return and the associated driver initialized.

Signed-off-by: Matt Porter <mporter@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>