greybus: protocol: split binding of prototcols to connections out of init

When adding a new protocol to the system, walk all bundles and try to
hook up any connections that do not have a protocol already.  This sets
the stage to allow for protocols to be loaded at any time, not just
before the device is seen in the system.

Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>