Spyglass violations in `idma_inst64_top`

[gbellocchi]

As the title reports, I found some Spyglass violations ('W123' and 'W287a') in idma_inst64_top while debugging the Snitch cluster (PR #330).

[DanielKellerM]

Thank you for reporting this. Could you target https://github.com/pulp-platform/iDMA/tree/__deploy__88b51c5__fix/inst64-init-write-rsp in your PR and test it out? The init protocol write manager wasnt used and it was triggering spyglass.