Generating Odin export fails due to mismatch in names

Although devicepkg-dev does not append the flavor information in the downstream kernel (see https://gitlab.com/postmarketOS/pmaports/-/commit/50ee94d8e3609ff0f0db648e454c403b7749a87d), this change is not correctly applied at pmb/export/odin.py. As a result, when I want to export to Odin-flashable TAR file, it only produces empty TAR file. By dropping the flavor suffix in the said Python code, the export should work.