asahi: Pass through surface sample count

This makes PIPE_CAP_SURFACE_SAMPLE_COUNT do something, namely, explode
with lots of fireworks. We'll have to figure out what's wrong, but at
least now we aren't just not trying at all. Should not break anything as
long as PIPE_CAP_SURFACE_SAMPLE_COUNT is not flipped on.

Signed-off-by: Asahi Lina <lina@asahilina.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/23832>

src/gallium/drivers/asahi/agx_state.c

@@ -888,6 +888,7 @@ agx_create_surface(struct pipe_context *ctx, struct pipe_resource *texture,
 
    surface->context = ctx;
    surface->format = surf_tmpl->format;
+   surface->nr_samples = surf_tmpl->nr_samples;
    surface->width = u_minify(texture->width0, level);
    surface->height = u_minify(texture->height0, level);
    surface->texture = texture;