nfsd: Clean up errors in nfs4state.c

Fix the following errors reported by checkpatch:

ERROR: spaces required around that '=' (ctx:VxW)

ERROR: space required after that ',' (ctx:VxO)
ERROR: space required before that '~' (ctx:OxV)
Signed-off-by: KaiLong Wang <wangkailong@jari.cn>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>