Because of this, rename greybus_module_id to greybus_interface_block_id.
We still need to add a way for a "class" driver to be bound to an
interface, but for now, all we really need is the vendor/product pair as
the GP Bridge interface block is going to be our main user.
Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>