Sometimes it is useful to be able to find a block device without also
probing it. Add a function for this as well as the associated test.
Signed-off-by: Simon Glass <sjg@chromium.org>
Add some tests to check that block devices work as expected.
Signed-off-by: Simon Glass <sjg@chromium.org>
Tested-by: Stephen Warren <swarren@nvidia.com>