amd: add nir_intrinsic_xfb_counter_sub_amd and fix overflowed streamout offsets

Fixes: 5ec79f9899 - ac/nir/ngg: nogs support streamout

Reviewed-by: Qiang Yu <yuq825@gmail.com>
Reviewed-by: Timur Kristóf <timur.kristof@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/21584>

src/amd/compiler/aco_instruction_selection.cpp

@@ -9132,6 +9132,9 @@ visit_intrinsic(isel_context* ctx, nir_intrinsic_instr* instr)
       emit_split_vector(ctx, dst, instr->num_components);
       break;
    }
+   case nir_intrinsic_xfb_counter_sub_amd:
+      /* TODO: implement this */
+      break;
    case nir_intrinsic_memory_barrier_buffer: {
       wait_imm wait;
       wait.lgkm = 0;