anv: move utrace flush out of backends

The next patch is going to introduce some locking that needs to happen
before the submission to the backend.

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Acked-by: Emma Anholt <emma@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24744>
7 files changed