releasetools: Fix two minor issues with _LoadOemDicts().

The first one in WriteVerifyPackage() is mismatching function parameters
that can be trivially fixed.

The other one is in WriteABOTAPackageWithBrilloScript(), where we don't
have edify script instance.

Test: `pylint --rcfile=pylintrc ota_from_target_files.py`.
Change-Id: Ie238ef5b296dfe9e725b61376992447b662d2376