drm/ttm: fix memleak in ttm_transfered_destroy

We need to cleanup the fences for ghost objects as well.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reported-by: Erhard F. <erhard_f@mailbox.org>
Tested-by: Erhard F. <erhard_f@mailbox.org>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Bug: https://bugzilla.kernel.org/show_bug.cgi?id=214029
Bug: https://bugzilla.kernel.org/show_bug.cgi?id=214447
CC: <stable@vger.kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20211020173211.2247-1-christian.koenig@amd.com