driver matching: Greybus drivers bind to interface blocks, not modules

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.

Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>