NFS: Fix a number of sparse warnings

Fix a number of "warning: symbol 'foo' was not declared. Should it be
static?" conditions.

Fix 2 cases of "warning: Using plain integer as NULL pointer"

fs/nfs/delegation.c:263:31: warning: restricted fmode_t degrades to integer
  - We want to allow upgrades to a WRITE delegation, but should otherwise
    consider servers that hand out duplicate delegations to be borken.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs3acl.c

@@ -192,7 +192,7 @@ struct posix_acl *nfs3_proc_getacl(struct inode *inode, int type)
 		.pages = pages,
 	};
 	struct nfs3_getaclres res = {
-		0
+		NULL,
 	};
 	struct rpc_message msg = {
 		.rpc_argp	= &args,