binman: collection: Set build_done on referenced entries

binman: collection: Set build_done on referenced entries

The collection etype uses phandles in the 'content' property to
reference other entries. Mark each referenced entry with build_done
to avoid rebuilding the same entry data multiple times.

This is important for cases where rebuilding may change the data
content, e.g. due to timestamps or random IVs in encryption.

Refactor GetContentsByPhandle() to return both the entry object and
its data.

Signed-off-by: yan wang <yan.wang@softathome.com>
Reviewed-by: Simon Glass <sjg@chromium.org>