cifs: Throw -EOPNOTSUPP error on unsupported reparse point type from parse_reparse_point()

[ Upstream commit cad3fc0a ]

This would help to track and detect by caller if the reparse point type was
processed or not.

Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>