No compatibility with Efinity 2024.2.294

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There are multiple changes in 2024.2 that seem to break compatibility:

1. the pt/db/device_*.xml files are gone. This might be intentional, however, I just copied them over from the previous version for myself, which seems to help (will investigate further at some later point in time)
2. the vdb file is placed in the outflow directory, while litex expects it to be in work_syn. As a workaround, I added a check into my local codebase, whether the file exists in work_syn and use the outflow directory if it doesn't.