security: fix AES crypt final length calculation

Open-webOS-DCO-1.0-Signed-off-by: Janne Kiiski <janne.kiiski@lge.com>
Open-webOS-DCO-1.0-Signed-off-by: Janne Hurskainen <janne.hurskainen@lge.com>

Change-Id: Id767940f8c6eefc19db934f0d66af4af37445178
Reviewed-on: https://g2g.palm.com/1627
Reviewed-by: Build Verification
Reviewed-by: Janne Kiiski <janne.kiiski@lge.com>
Tested-by: Janne Kiiski <janne.kiiski@lge.com>
Reviewed-by: Janne Hurskainen <janne.hurskainen@lge.com>
Reviewed-by: Keith Derrick <keith.derrick@lge.com>
Reviewed-on: https://g2g.palm.com/2448
Tested-by: Janne Hurskainen <janne.hurskainen@lge.com>