iris: assert bufmgr->bo_deps_lock is held

This is the only place that touches bo->deps but does not explicitly
lock it and is not a setup/teardown function where locking won't help
anything.

I'm confident we won't hit this assertion, but I've recently had this
lock as the suspect of a bug and had to check the callers to see if we
could be calling from any unlocked place. Having the assert helps
increasing our confidence.

Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/25236>

src/gallium/drivers/iris/iris_batch.c

@@ -744,6 +744,8 @@ update_bo_syncobjs(struct iris_batch *batch, struct iris_bo *bo, bool write)
    struct iris_bufmgr *bufmgr = screen->bufmgr;
    struct iris_context *ice = batch->ice;
 
+   simple_mtx_assert_locked(iris_bufmgr_get_bo_deps_lock(bufmgr));
+
    /* Make sure bo->deps is big enough */
    if (screen->id >= bo->deps_size) {
       int new_size = screen->id + 1;