nak: use assert_eq!(a, b) instead of assert!(a == b)

Tells you what's different when it fails.

Suggested-by: @LingMan
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/38807>

src/nouveau/compiler/nak/ssa_value.rs

@@ -314,7 +314,7 @@ fn test_ssa_ref_round_trip() {
             .collect();
 
         let ssa_ref = SSARef::new(&vec);
-        assert!(ssa_ref[..] == vec[..]);
+        assert_eq!(ssa_ref[..], vec[..]);
     }
 }