nak/ra: Never move uniform regs in non-uniform blocks

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/29591>

src/nouveau/compiler/nak/assign_regs.rs

@@ -1144,6 +1144,13 @@ impl AssignRegsBlock {
                         annotation: "generated by assign_regs".into(),
                     }));
                 }
+                if !b.uniform {
+                    for dst in pcopy.dsts_as_slice() {
+                        if let Dst::Reg(reg) = dst {
+                            assert!(!reg.is_uniform());
+                        }
+                    }
+                }
                 instrs.push(Instr::new_boxed(pcopy));
             }