kbfs_ops: fix defer log error printing
kbfs_ops: fix defer log error printing

Suggested by akalin-keybase.

Issue: #630

keybase/client,keybase/client,keybase/client,keybase/kbfs,keybase/kbfs,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/kbfs,keybase/kbfs,keybase/client,keybase/client,keybase/client