drivers: base: test: Add ...find_device_by...(... NULL) tests

drivers: base: test: Add ...find_device_by...(... NULL) tests

We recently updated these device_match*() (and therefore, various
*find_device_by*()) functions to return a consistent 'false' value when
trying to match a NULL handle. Add tests for this.

This provides regression-testing coverage for the sorts of bugs that
underly commit 5c8418cf4025 ("PCI/pwrctrl: Unregister platform device
only if one actually exists").

Reviewed-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Brian Norris <briannorris@chromium.org>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Reviewed-by: David Gow <davidgow@google.com>
Link: https://lore.kernel.org/r/20241216201148.535115-4-briannorris@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>