ceph: always update atime/mtime/ctime for new inode

For new inode, atime/mtime/ctime are uninitialized.  Don't compare
against them.

Cc: stable@kernel.org
Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>