dtoc: Support scanning of uclasses

Uclasses can have per-device private / platform data so dtoc needs to
scan these drivers. This allows it to find out the size of this data so
it can be allocated a build time.

Add a parser for uclass information, similar to drivers. Keep a dict of
the uclasses that were found.

Signed-off-by: Simon Glass <sjg@chromium.org>
2 files changed