greybus: interface: separate disabling from removal

Separate interface disable from interface removal.

Disabling an interface means tearing down its control connection and
destroying (i.e. deregistering and releasing) its bundles, while
removing it means deregistering and releasing the interface itself.

This is needed to implement controlled module removal, where the module
interfaces are disabled before being physically ejected.

Signed-off-by: Johan Hovold <johan@hovoldconsulting.com>
Reviewed-by: Jeffrey Carlyle <jcarlyle@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>