ACPI: Drop ACPI device .bind() and .unbind() callbacks

Drop the .bind() and .unbind() that have no more users from
struct acpi_device_ops and remove all of the code referring to
them from drivers/acpi/scan.c.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Yinghai Lu <yinghai@kernel.org>
Acked-by: Toshi Kani <toshi.kani@hp.com>