greybus: interface: rename greybus_interface_block_id to greybus_interface_id

This moves the id structure name to not have "block" in it, as that
doesn't make sense anymore with the renaming of the gb_interface
structure.

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