ac/nir: fix partial mesh shader output writes on GFX11

Fixes dEQP-VK.mesh_shader.ext.smoke.monolithic.mesh_shader_triangle with
nir_opt_combine_stores disabled.

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Timur Kristóf <timur.kristof@gmail.com>
Fixes: 240e16fc8e ("ac/nir/ngg: Use attribute ring for mesh shader params.")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/25530>
(cherry picked from commit 2d98236dd5)

.pick_status.json

@@ -64,7 +64,7 @@
         "description": "ac/nir: fix partial mesh shader output writes on GFX11",
         "nominated": true,
         "nomination_type": 1,
-        "resolution": 0,
+        "resolution": 1,
         "main_sha": null,
         "because_sha": "240e16fc8e27ba76afa1bf5adbd6d70c680027ac",
         "notes": null

src/amd/common/ac_nir_lower_ngg.c

@@ -3903,6 +3903,7 @@ ms_store_arrayed_output_intrin(nir_builder *b,
       nir_def *soffset = nir_load_ring_attr_offset_amd(b);
       nir_store_buffer_amd(b, store_val, ring, base_addr_off, soffset, arr_index,
                            .base = const_off + param_offset * 16,
+                           .write_mask = write_mask,
                            .memory_modes = nir_var_shader_out,
                            .access = ACCESS_COHERENT | ACCESS_IS_SWIZZLED_AMD);
    } else if (out_mode == ms_out_mode_var) {