Revert "Revert "tmpfiles.d: adjust /dev/vfio/vfio access mode""

Revert "Revert "tmpfiles.d: adjust /dev/vfio/vfio access mode""

This reverts commit 33b91308c26ca5d512e43b6b32d596a2c9237d04.

The commit b42482af904ae0b94a6e4501ec595448f0ba1c06 dropped
'--exclude-prefix=/dev' from systemd-tmpfiles-setup.service. So, the
possibly later invocation of the service changes the permission set by
udevd.

As commmented in the head of this file, settings should be consistent
with udev rules. Only missing entry here is vfio. Let's re-add the
entry for the device.

Addresses https://github.com/systemd/systemd/pull/28681#issuecomment-1666949888.