rc.sensors: try starting iis2mdc

[AlexKlimaj]

The new ARK SAM GPS uses the iis2mdc over I2C directly.

[dakejahl]

I recently discovered that the lis2mdl and iis2mdc are identical from a software perspective. Do we want to keep both drivers around @dagar? This means running the iis2mdc driver will detect an lis2mdl as an iis2mdc
https://www.st.com/resource/en/design_tip/dt0131-digital-magnetometer-and-ecompass-efficient-design-tips--stmicroelectronics.pdf

[dagar]

If they're actually identical we can't really be probing both here.

Literally identical 100% or any actual differences?

[AlexKlimaj]

Sounds like identical from a firmware perspective. But I think the actual manufacturing of the MEMs is different.

[AlexKlimaj]

It looks like the lis2mdl isn't included in common magnetometers. I've updated rc.sensors to try starting the iis2mdc first, then trying the lis2mdl if it fails.

[dakejahl]

I think ideally we'd have only one driver, but I wrote the iis2mdc because I didn't even realize they were the same part. So maybe ideally one driver with a nice comment at the top referencing the support for those multiple devices. And then we delete the duplicate?