Make I2C transactions continuous according to specification (#740)

[fko-kuptec]

Summary

Changes the implementation of the ehal::i2c::I2c::transaction method to match the specification. The corresponding issue is #740.

I would be thankful if someone could have a look at it, to make sure that it now actually matches the specified behaviour. My code seems works now, but I might have misunderstood something.

Checklist

• CHANGELOG.md for the BSP or HAL updated
• All new or modified code is well documented, especially public items
• No new warnings or clippy suggestions have been introduced - CI will deny clippy warnings by default! You may #[allow] certain lints where reasonable, but ideally justify those with a short comment.

[jbeaurivage]

Hi @fko-kuptec, I agree with what you said in #740. Let me check if this PR actually does achieve that, I can potentially test with a logic analyzer some time next week.

[fko-kuptec]

Hi @fko-kuptec, I agree with what you said in #740. Let me check if this PR actually does achieve that, I can potentially test with a logic analyzer some time next week.

Thank you 😊