fix the build
  fs: ecryptfs: initialize payload_len in keystore.c

    This is meant to remove a compiler warning.  It should not make any
    functional change.

    payload_len should be initialized when it is passed to
    write_tag_64_packet() as a pointer.  If that call fails, this function
    should return early, and payload_len won't be used.

    The warning is:
    fs/ecryptfs/keystore.c:1168:28: warning: 'payload_len' may be used
    uninitialized in this function [-Wmaybe-uninitialized]