NFSv4.2 fix memory leak in nfs42_ssc_open

Static analysis with Coverity detected a memory leak

Reported-by: Colin King <colin.king@canonical.com>
Fixes: ec4b0925 ("NFS: inter ssc open")
Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>