Cvxif user interface

Created by: GuillaumeChauvon

Hello, @Silabs-ArjanB @davideschiavone @JeanRochCoulon @vogelpi @treforsouthwell

I added a user interface to the specification.

This interface allows to communicate user data from the core to the coprocessor and to obtain a possible response. It gives a new possibility to communicate with the coprocessor for custom purposes.

It will make the build of an interconnect for identical coprocessor much easier. I also believe it can have much more use for example :

• Set or modify parameters in the coprocessor without instruction
• Access a coprocessor register without instruction

Regards, Guillaume Chauvon Intern at Thales DIS Design Services