This adds a framework for en/decrypting data blobs. Some SoCs have
support for hardware crypto engines that can en/decrypt using keys
that a tied to the SoC and are visible for the crypto hardware only.
With this patch it's possible to encrypt confidential data using
these keys and to decrypt it later for usage.

Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>