[EMCIO] Remove various obsolete references to io and iov2

[Sigma1912]

This PR removes obsolete references to 'io' and 'iov2'

Background:
'io' and 'iov2' have been removed and their functionality moved to task:
9d79c2a

Discussion see:
#3167

[Sigma1912]

Not sure why some of these tests are failing. Seems build and test just fine on my local machine.

[andypugh]

Not sure why some of these tests are failing. Seems build and test just fine on my local machine.

When I last looked it seemed to be a problem with the Ubuntu VM not finding a Firefox snap to install.

[Sigma1912]

Thanks for the comment. It seems to have smoothed itself out now.

[hansu]

iocontrol.1.adoc can also be removed I think. But we should link iocontrol to io by adding it to the name section:

io(1)
NAME
+ io, iocontrol - interacts with HAL or G-code in non-realtime
- io - interacts with HAL or G-code in non-realtime

[hansu]

po4a.cfg:170: The master file 'src/man/man1/iocontrol.1.adoc' does not exist.

Sorry you have to remove it from the po4a.cfg as well.

[Sigma1912]

Looking at this commit by @rene-dev makes me think that the [EMCIO] 'CYCLE_TIME = 0.100' entry should also be removed.
27ef544#diff-53c30ad3a9ebf3f0b298246f7bec4fc2599bfdad79ae2334ed89dfad9ee6f2a6L1347

[rene-dev]

Yes, emcio cycle time can be removed as well.

[Sigma1912]

This is ready, as far as I'm concerned.