tmc2240: add ADC voltage formatters

[kdomanski]

ADC values will be shown in Volts.

Output sample:

// ADC_VSUPPLY_AIN: 02d709b7 adc_vsupply=0x09b7(24.203V) adc_ain=0x02d7(221.880mV)

[github-actions]

Thank you for your contribution to Klipper. Unfortunately, a reviewer has not assigned themselves to this GitHub Pull Request. All Pull Requests are reviewed before merging, and a reviewer will need to volunteer. Further information is available at: https://www.klipper3d.org/CONTRIBUTING.html

There are some steps that you can take now:

1. Perform a self-review of your Pull Request by following the steps at: https://www.klipper3d.org/CONTRIBUTING.html#what-to-expect-in-a-review
   If you have completed a self-review, be sure to state the results of that self-review explicitly in the Pull Request comments. A reviewer is more likely to participate if the bulk of a review has already been completed.
2. Consider opening a topic on the Klipper Discourse server to discuss this work. The Discourse server is a good place to discuss development ideas and to engage users interested in testing. Reviewers are more likely to prioritize Pull Requests with an active community of users.
3. Consider helping out reviewers by reviewing other Klipper Pull Requests. Taking the time to perform a careful and detailed review of others work is appreciated. Regular contributors are more likely to prioritize the contributions of other regular contributors.

Unfortunately, if a reviewer does not assign themselves to this GitHub Pull Request then it will be automatically closed. If this happens, then it is a good idea to move further discussion to the Klipper Discourse server. Reviewers can reach out on that forum to let you know if they are interested and when they are available.

Best regards,
~ Your friendly GitIssueBot

PS: I'm just an automated script, not a human being.

[kdomanski]

Self-review checklist

1. Is the submission free of defects and is it ready to be widely deployed?

• Yes, the submission passes regression tests
• it has been tested manually as well
• it doesn't add any logging or debugging code

2. Does the submission provide a "high impact" benefit to real-world users performing real-world tasks?

Yes, it prevents the necessity to manually calculate voltage values when debugging the behavior of TMC2240 drivers - in only 2 lines of code.

3. Is the copyright of the submission clear, non-gratuitous, and compatible?

Yes.

4. Does the submission follow guidelines specified in the Klipper documentation?

Yes.

5. Is the Klipper documentation updated to reflect new changes?

The completeness of field formatters is not documented nor does it need to be. Thus adding a few formatters requires no documentation change.

6. Are commits well formed, address a single topic per commit, and independent?

Yes.

[KevinOConnor]

Thanks.

-Kevin