driver core: remove subsys_find_device_by_id()

This function has not been called by any code in the kernel tree in many
many years so remove it as it is unused.

Reviewed-by: Rafael J. Wysocki <rafael@kernel.org>
Link: https://lore.kernel.org/r/20230109175810.2965448-2-gregkh@linuxfoundation.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>