drm/ttm: handle undefined printf arg evaluation order in debugfs

drm/ttm: handle undefined printf arg evaluation order in debugfs

When you read this debugfs file it's isn't guaranteed the count
will happen before the scan, but I think the intent is that it does.

printf argument evaluation order is undefined.

Cc: Christian Koenig <christian.koenig@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Link: https://lore.kernel.org/r/20250603220901.1217161-1-airlied@gmail.com