Acceleration device class

[joshurtree]

I'm trying to get this quirk working. It relies on SensorDeviceClass.ACCELERATION that was added in this commit last year but it has subsequently been removed by this commit. Was this intentional?

[puddly]

ZHA mirrors the Home Assistant device classes and units. I don't think Home Assistant currently has an acceleration device class (or had one in the past, according to Git history?).

[TheJulianJES]

It was added with this PR zigpy/zigpy#1585, but correctly removed later, as HA doesn't have an acceleration device class. We can't support anything that HA doesn't support.

[jezzaaa]

I've updated the quirk in the PR to no longer reference the accel device class.

[jezzaaa]

The PR is ready to merge, @TheJulianJES. Is there anything remaining to do?