greybus: get rid of functions now...

greybus: get rid of functions now...

We decided yesterday that we would no longer support the notion of a
"function."  Instead, a connection will simply exist between the AP
and an interface on a module (and a CPort Id on each end).  What
was previously considered the "function type" will now be handled
as the "protocol" associated with the connection.

Update gb_connection_create() to take just the interface and a cport
id associated with that interface.

Right now every module points back to a host device, so for now
we'll establish the connection back to that.

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