Implement XCValu intrinsics for CV32E40P according to the specification.
This is a commit of the patch-set to upstream the 7 vendor specific extensions of CV32E40P.
Contributors: @CharKeaney, Nandni Jamnadas, Serkan Muhcu, @jeremybennett, @lewis-revill, @liaolucy, @simoncook, @xmj
Keep this with the other XCV extensions