schemas: i2c: Add transfer timeout property to controller

[tleb]

Add i2c-transfer-timeout-us property to i2c-controller.yaml signaling the number of microseconds to wait before considering an I2C transfer has failed. Unit is microseconds (µs).

See the original proposal on lkml for context, with its answers. Original proposal was to add the property to a specific I2C bus controller.

Draft because

• Feedback from Linux I2C subsystem maintainers would be useful to confirm this goes in the right direction.
• Should the prop be added to the not-required list? I am not familiar with this reverse syntax and its meaning.

[robherring]

Draft because

* Feedback from Linux I2C subsystem maintainers would be useful to confirm this goes in the right direction.

Wolfram gave his Reviewed-by. Please add it here.

* Should the prop be added to the not-required list? I am not familiar with this reverse syntax and its meaning.

No, that is just saying those 2 properties are mutually exclusive.

[tleb]

Reviewed-By Wolfram got added and I removed the draft status. Thanks Rob.