Replace pkg/micro-ecc random calls

[d00616]

periph/random needs an higher level API. If this implemented this API needs to be integrated into micro-ecc.
#2236 (comment)

[LudwigKnuepfer]

I'm not going to work on this any time soon.

[miri64]

Maybe #5153?

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. If you want me to ignore this issue, please mark it with the "State: don't stale" label. Thank you for your contributions.