[dv/adc_ctrl] Moving assertions to RTL or interface for reusability

[cindychip]

Detailed discussion here:
#11744

[andreaskurth]

Triaged for adc_ctrl. I think this is not necessary for M2.5, so I'm labeling it Type:Icebox Changes deferred to future milestones . @cindychip if you disagree, PLMK

[johngt]

At this stage - moving assertions to RTL is not going to be done as an ECO so should be considered for future release.
@moidx / @vogelpi / @andreaskurth

[matutem]

Can someone clarify which assertions this refers to? There are some assertions for the adc_ctrl fsm that are written in a module at https://github.com/lowRISC/opentitan/blob/master/hw/ip/adc_ctrl/dv/sva/adc_ctrl_fsm_sva.sv, but could be moved to an interface, which is simple. Other assertions are in the tb.sv file, and I imagine these are the assertions relevant to this issue.

[vogelpi]

I think it's probably both the assertions inside tb.sv as well as the ones inside adc_ctrl_fsm_sva.sv. But I seriously think we have more important things to do right now. Let's not bother about this now.