kselftest: Add new test for detecting unprobed Devicetree devices

Introduce a new kselftest to detect devices that were declared in the
Devicetree, and are expected to be probed by a driver, but weren't.

The test uses two lists: a list of compatibles that can match a
Devicetree device to a driver, and a list of compatibles that should be
ignored. The first is automatically generated by the
dt-extract-compatibles script, and is run as part of building this test.
The list of compatibles to ignore is a hand-crafted list to capture the
few exceptions of compatibles that are expected to match a driver but
not be bound to it.

Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/20230828211424.2964562-4-nfraprado@collabora.com
Signed-off-by: Rob Herring <robh@kernel.org>