r300: disable microtiling for scanout buffers

Does not work with R300/R400 due to kernel driver limitations.
Suggested by Marek Olšák.

Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/12010
Fixes: f424ef1801
Signed-off-by: Pavel Ondračka <pavel.ondracka@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32638>

src/gallium/drivers/r300/r300_texture_desc.c

@@ -510,11 +510,12 @@ static void r300_setup_tiling(struct r300_screen *screen,
             break;
 
         case 2:
-            tex->tex.microtile =
-                tex->b.bind & PIPE_BIND_SCANOUT ?
-                     RADEON_LAYOUT_TILED : RADEON_LAYOUT_SQUARETILED;
+            tex->tex.microtile = RADEON_LAYOUT_SQUARETILED;
             break;
     }
+    if (tex->b.bind & PIPE_BIND_SCANOUT) {
+        tex->tex.microtile = RADEON_LAYOUT_LINEAR;
+    }
 
     if (dbg_no_tiling) {
         return;