ARM: sun7i: dt: Add Security System to A20 SoC DTS

The Security System is a hardware cryptographic accelerator that support
AES/MD5/SHA1/DES/3DES/PRNG algorithms.
It could be found on many Allwinner SoC.

This patch enable the Security System on the Allwinner A20 SoC Device-tree.

Signed-off-by: LABBE Corentin <clabbe.montjoie@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>