turnip: move a comment about FMT6_Z24_UNORM_S8_UINT_AS_R8G8B8A8

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/21117>

src/freedreno/fdl/fd6_view.c

@@ -226,6 +226,10 @@ fdl6_view_init(struct fdl6_view *view, const struct fdl_layout **layouts,
       swap = WZYX;
    }
 
+   /* FMT6_Z24_UNORM_S8_UINT_AS_R8G8B8A8 is broken without UBWC on a630.  We
+    * don't need it without UBWC anyway because the purpose of the format is
+    * UBWC-compatibility.
+    */
    if (texture_format == FMT6_Z24_UNORM_S8_UINT_AS_R8G8B8A8 && !ubwc_enabled)
       texture_format = FMT6_8_8_8_8_UNORM;
 

src/freedreno/vulkan/tu_image.c

@@ -353,9 +353,6 @@ ubwc_possible(struct tu_device *device,
     *
     * If we wish to get the border colors correct without knowing the format
     * when creating the sampler, we also have to use the A630 workaround.
-    *
-    * Additionally, the special AS_R8G8B8A8 format is broken without UBWC,
-    * so we have to fallback to 8_8_8_8_UNORM when UBWC is disabled
     */
    if (!use_z24uint_s8uint &&
        format == VK_FORMAT_D24_UNORM_S8_UINT &&