nak: Fix a SM check for OpPCnt

This doens't really fix anything as we don't have any nir_loops on
Volta+ but the code was wrong so we should fix it.

Fixes: 9bbc692064 ("nak/nir: Rework CRS handling")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34201>

src/nouveau/compiler/nak/from_nir.rs

@@ -3434,7 +3434,7 @@ impl<'a> ShaderFromNir<'a> {
             b.push_op(phi);
         }
 
-        if self.sm.sm() < 75 && nb.cf_node.prev().is_none() {
+        if self.sm.sm() < 70 && nb.cf_node.prev().is_none() {
             if let Some(_) = nb.parent().as_loop() {
                 b.push_op(OpPCnt {
                     target: self.get_block_label(nb),