driver core: add a faux bus for use when a simple device/bus is needed

driver core: add a faux bus for use when a simple device/bus is needed

Many drivers abuse the platform driver/bus system as it provides a
simple way to create and bind a device to a driver-specific set of
probe/release functions.  Instead of doing that, and wasting all of the
memory associated with a platform device, here is a "faux" bus that
can be used instead.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: Zijun Hu <quic_zijuhu@quicinc.com>
Link: https://lore.kernel.org/r/2025021026-atlantic-gibberish-3f0c@gregkh
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>