drm/ttm: never consider pinned BOs for eviction&swap

There is a small window where we have already incremented the pin count
but not yet moved the bo from the lru to the pinned list.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reported-by: Pelloux-Prayer, Pierre-Eric <Pierre-eric.Pelloux-prayer@amd.com>
Tested-by: Pelloux-Prayer, Pierre-Eric <Pierre-eric.Pelloux-prayer@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Link: https://patchwork.freedesktop.org/patch/msgid/20230707120826.3701-1-christian.koenig@amd.com