rp2040 correct dcd_edpt_iso_activate

[pschatzmann]

Describe the PR
I think your last redesign of my iso implementation has introduced an error. The audio is not wokring any more.
This PR resolves the issue.

Additional context
See these comments
#2838

[HiFiPhile]

Thank you for the fix, I did a forced push to fix the CI.

It seems strange to add hw_endpoint_init() in dcd_edpt_iso_activate()since it has already been called indcd_edpt_iso_alloc()`, beside packet size is there anything changed between these calls ?

[pschatzmann]

I did not double check this: I just added it back because it was also there before the change and removing it was breaking it from working properly.