ceph: silence smatch warning in reconnect_caps_cb()

Smatch static checker warning:

  fs/ceph/mds_client.c:3968 reconnect_caps_cb()
  warn: missing error code here? '__get_cap_for_mds()' failed. 'err' = '0'

[ idryomov: Dan says that Smatch considers it intentional only if the
  "ret = 0;" assignment is within 4 or 5 lines of the goto. ]
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/mds_client.c

@@ -3942,7 +3942,7 @@ static int reconnect_caps_cb(struct inode *inode, int mds, void *arg)
 	struct dentry *dentry;
 	struct ceph_cap *cap;
 	char *path;
-	int pathlen = 0, err = 0;
+	int pathlen = 0, err;
 	u64 pathbase;
 	u64 snap_follows;
 
@@ -3965,6 +3965,7 @@ static int reconnect_caps_cb(struct inode *inode, int mds, void *arg)
 	cap = __get_cap_for_mds(ci, mds);
 	if (!cap) {
 		spin_unlock(&ci->i_ceph_lock);
+		err = 0;
 		goto out_err;
 	}
 	dout(" adding %p ino %llx.%llx cap %p %lld %s\n",