ceph: don't WARN when removing caps due to blocklisting

We expect to remove dirty caps when the client is blocklisted. Don't
throw a warning in that case.

[ idryomov: break unnecessarily long line ]

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>