panfrost: add earlyzs FPK condition for v6-

While v7+ checks this on HW, older architectures depend on SW to do it.

Fixes: c43882ad54 ("panfrost: Allow pixels using discard to be killed")
Reviewed-by: Lars-Ivar Hesselberg Simonsen <lars-ivar.simonsen@arm.com>
Reviewed-by: Faith Ekstrand <faith.ekstrand@collabora.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Yiwei Zhang <zzyiwei@chromium.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/38522>

src/gallium/drivers/panfrost/pan_jm.c

@@ -587,7 +587,11 @@ jm_emit_tiler_draw(struct mali_draw_packed *out, struct panfrost_batch *batch,
 
          cfg.flags_0.allow_forward_pixel_to_kill =
             pan_allow_forward_pixel_to_kill(ctx, fs);
-         cfg.flags_0.allow_forward_pixel_to_be_killed = !fs->info.writes_global;
+
+         /* early ZS check for FPK is performed by HW on v7+ */
+         cfg.flags_0.allow_forward_pixel_to_be_killed =
+            !fs->info.writes_global &&
+            ((PAN_ARCH > 6) || earlyzs.kill != MALI_PIXEL_KILL_FORCE_LATE);
 
          /* Mask of render targets that may be written. A render
           * target may be written if the fragment shader writes