NFSv4 only print the label when its queried

stable inclusion
from linux-4.19.230
commit 1789f59f1779c99d0756b40036c62a7519f53543

--------------------------------

[ Upstream commit 2c52c8376db7160a1dd8a681c61c9258405ef143 ]

When the bitmask of the attributes doesn't include the security label,
don't bother printing it. Since the label might not be null terminated,
adjust the printing format accordingly.

Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>
Signed-off-by: Laibin Qiu <qiulaibin@huawei.com>