drm/nouveau/sched: Don't pass user flags to drm_syncobj_find_fence()

The flags field in drm_syncobj_find_fence() takes SYNCOBJ_WAIT flags
from the syncobj UAPI whereas sync->flags is from the nouveau UAPI. What
we actually want is 0 flags which tells it to just try to find the
fence and then return without waiting.

Fixes: b88baab8 ("drm/nouveau: implement new VM_BIND uAPI")
Cc: Danilo Krummrich <dakr@redhat.com>
Cc: Dave Airlie <airlied@redhat.com>
Reviewed-by: Danilo Krummrich <dakr@redhat.com>
Signed-off-by: Faith Ekstrand <faith.ekstrand@collabora.com>
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230807234210.175968-1-faith.ekstrand@collabora.com