ceph: initialize superblock s_time_gran to 1

Having granularity set to 1us results in having inode timestamps with a
accurancy different from the fuse client (i.e. atime, ctime and mtime will
always end with '000').  This patch normalizes this behaviour and sets the
granularity to 1.
Signed-off-by: Luis Henriques <lhenriques@suse.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Sage Weil <sage@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/super.c

@@ -980,7 +980,7 @@ static int ceph_set_super(struct super_block *s, void *data)
 	s->s_d_op = &ceph_dentry_ops;
 	s->s_export_op = &ceph_export_ops;
 
-	s->s_time_gran = 1000;  /* 1000 ns == 1 us */
+	s->s_time_gran = 1;
 
 	ret = set_anon_super(s, NULL);  /* what is that second arg for? */
 	if (ret != 0)