SQUASH: client: querying for stx_version field requires getting all shared caps

SQUASH: client: querying for stx_version field requires getting all shared caps

Otherwise, someone could potentially query for just CEPH_STATX_VERSION,
and see it as unchanged, even when there are changes buffered up on
other clients.

By doing this, I don't think we'll incur any perf hit in the common use
case which is ganesha querying for all attributes. We are adding Xs
here, but unless there is a lot of xattr activity I don't think that
will generally cause a lot of exclusive cap recalls.

Also, we don't actually need AUTH caps to fetch CEPH_STATX_RDEV, remove
that from statx_to_mask. PIN is sufficient there.

Signed-off-by: Jeff Layton <jlayton@redhat.com>