nfsd: avoid pointless cred reference count bump

The code already got rid of the extra reference count from the old
version of override_creds().

Link: https://lore.kernel.org/r/20241125-work-cred-v2-28-68b9d38bb5b2@kernel.org
Acked-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Christian Brauner <brauner@kernel.org>

Author: brauner

fs/nfsd/auth.c

@@ -79,8 +79,7 @@ int nfsd_setuser(struct svc_cred *cred, struct svc_export *exp)
 	else
 		new->cap_effective = cap_raise_nfsd_set(new->cap_effective,
 							new->cap_permitted);
-	put_cred(override_creds(get_new_cred(new)));
-	put_cred(new);
+	put_cred(override_creds(new));
 	return 0;
 
 oom: