drm/ttm: use ttm_resource_unevictable() to replace pin_count and swapped

TTM always uses pin_count and ttm_resource_is_swapped() together to
determine whether a BO is unevictable.
Now use ttm_resource_unevictable() to replace them.

Signed-off-by: Zhaoyu Liu <liuzhaoyu.zackary@bytedance.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250126093256.GA688734@bytedance


Signed-off-by: Christian König <christian.koenig@amd.com>