panfrost: Set zs_samples as necessary

Fixes MSAA Z/S.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5929>
diff --git a/src/gallium/drivers/panfrost/pan_mfbd.c b/src/gallium/drivers/panfrost/pan_mfbd.c
index e1c389c..247dfd1 100644
--- a/src/gallium/drivers/panfrost/pan_mfbd.c
+++ b/src/gallium/drivers/panfrost/pan_mfbd.c
@@ -285,6 +285,15 @@
         bool is_bifrost = dev->quirks & IS_BIFROST;
         struct panfrost_resource *rsrc = pan_resource(surf->texture);
 
+        unsigned nr_samples = surf->nr_samples;
+
+        if (!nr_samples)
+                nr_samples = surf->texture->nr_samples;
+
+        nr_samples = MAX2(nr_samples, 1);
+
+        fbx->zs_samples = MALI_POSITIVE(nr_samples);
+
         unsigned level = surf->u.tex.level;
         unsigned first_layer = surf->u.tex.first_layer;
         assert(surf->u.tex.last_layer == first_layer);
@@ -315,11 +324,6 @@
 
                 int stride = rsrc->slices[level].stride;
 
-                unsigned nr_samples = surf->nr_samples;
-
-                if (!nr_samples)
-                        nr_samples = surf->texture->nr_samples;
-
                 unsigned layer_stride = (nr_samples > 1) ? rsrc->slices[level].size0 : 0;
 
                 fb->mfbd_flags |= MALI_MFBD_EXTRA | MALI_MFBD_DEPTH_WRITE;