nak: Don't mix up two types of barrier

This part of the shader header is used for control flow barriers (like
glsl barrier()), not reconvergence barriers.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30180>

src/nouveau/compiler/nak/assign_regs.rs

@@ -1359,13 +1359,6 @@ impl Shader<'_> {
 
         self.info.num_gprs = total_gprs.try_into().unwrap();
 
-        // We do a maximum here because nak_from_nir may set num_barriers to 1
-        // in the case where there is an OpBar.
-        self.info.num_barriers = max(
-            self.info.num_barriers,
-            max_live[RegFile::Bar].try_into().unwrap(),
-        );
-
         let limit = PerRegFile::new_with(|file| {
             if file == RegFile::GPR {
                 gpr_limit