staging-slicoss: Replace variable initialisations by assignments in slic_if_init()

[SF Markus Elfring]

>> Which measurement results would you accept for further discussion?
> 
> If you don't know how to show your results, then this whole discussion
> is pointless.

I could show test results. But it could happen that I would choose insufficient
variations for execution environments.

I am unsure about the requested detail and size around test parameters.

Regards,
Markus