Issue 2675 correctly reverse fixed size datatypes

[igorbga]

As a response to issue #2675 this PR improves "convert_to_registers" in order to do the reversing of the bytes per word, and not for the complete data array.

String and bit fields might vary in size and way of handling so I didn't dare to change anything about then in this MR, it just works with datatypes that have a fixed known size.

fixes #2675

[igorbga]

The remaining CI fails are related to code prior to my Pull Request so, although the suggested changes sound very reasonable to me, I didn't dare to change it.

Let me know if you'd rather have me also change those couple of lines.

[janiversen]

PR looks good apart from one small comment.

But you need to add tests to show it works as expected. We have a demand for 100% test coverage plus functionality test for all rewritten modules.

[janiversen]

Please combine the 2 lines using the := operator.

[janiversen]

The remaining CI fails are related to code prior to my Pull Request so, although the suggested changes sound very reasonable to me, I didn't dare to change it.

Let me know if you'd rather have me also change those couple of lines.

We do not merge anything without a clear CI (and tests depending on the module).

[janiversen]

And just fyi, line 781 in mixin.py is your code !

The other reported error is a side effect that goes away when your code passes.

[janiversen]

LGTM, thanks.