gv100/ir: noop OP_BAR for now

Let's get stuff rolling and deal with figuring this out later.

Acked-by: M Henning <drawoc@darkrefraction.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17633>

src/nouveau/codegen/nv50_ir_emit_gv100.cpp

@@ -1583,6 +1583,12 @@ CodeEmitterGV100::emitBAR()
 {
    uint8_t subop, redop = 0x00;
 
+   //XXX: ILLEGAL_INSTR_PARAM - why?
+   if (targ->getChipset() >= 0x170) {
+      emitNOP();
+      return;
+   }
+
    // 80
    //    01: DEFER_BLOCKING
    // 78:77