Don't allow start_bdf with new auto max bus detection code.

Don't allow start_bdf with new auto max bus detection code.

It's not valid to set a "start bdf" when search for a device now,
    because we wont be able to properly detect the maximum bus unless
    we start at the beginning.
Change callers that need to resume a search to use foreachpci() macro.
Update all callers so that they don't pass in the now unused start_bdf.