binman: Put our local modules ahead of system modules

If a system module is named the same as one of those used by binman we
currently pick the system module. Adjust the ordering so that our modules
are chosen instead.

The module conflict reported was 'tools' from jira-python. I cannot access
that package to test it.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reported-by: Kevin Hilman <khilman@baylibre.com>
Acked-by: Kevin Hilman <khilman@baylibre.com>