FenceiAssert - Check Handshake vs RVFI

Created by: silabs-robin

This PR adds one assert to the fencei assertion set.

As mentioned by @silabs-oysteink, there is a problem that the RTL treats fence as fencei. The original fencei asserts probed some internal signals and did not double check against RVFI! @silabs-mateilga, @silabs-krdosvik, @MikeOpenHWGroup, I would appreciate a review and merge. (Very little code to review.)