ARef is defined in sync and is getting used from types causing the
build to fail.
Fix this by using ARef from sync module.
Fixes: 80df573af9 ("rust: drm: gem: shmem: Add DRM shmem helper abstraction")
Signed-off-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Link: https://patch.msgid.link/20260426094725.2188668-2-mkchauras@gmail.com
[ Add missing Fixes: tag. - Danilo ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>