ubifs: Fix directory size calculation for symlinks

ubifs: Fix directory size calculation for symlinks

BugLink: https://bugs.launchpad.net/bugs/1835972
commit 00ee8b60102862f4daf0814d12a2ea2744fc0b9b upstream.

We have to account the name of the symlink and not the target length.

Fixes: ca7f85be8d6c ("ubifs: Add support for encrypted symlinks")
Cc: <stable@vger.kernel.org>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>