firmware: xilinx: Add ZynqMP aes API for AES functionality

Add ZynqMP firmware AES API to perform encryption/decryption of given data.

Signed-off-by: Kalyani Akula <kalyani.akula@xilinx.com>
Acked-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>