driver core: make bus_get_device_klist() static

No one calls this function outside of drivers/base/bus.c so make it
static so it does not need to be exported anymore.

Reviewed-by: Rafael J. Wysocki <rafael@kernel.org>
Link: https://lore.kernel.org/r/20230109175810.2965448-1-gregkh@linuxfoundation.org


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