NFSD: Fix sparse warning

/home/cel/src/linux/linux/fs/nfsd/nfs4proc.c:1539:24: warning: incorrect type in assignment (different base types)
/home/cel/src/linux/linux/fs/nfsd/nfs4proc.c:1539:24:    expected restricted __be32 [usertype] status
/home/cel/src/linux/linux/fs/nfsd/nfs4proc.c:1539:24:    got int

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>