af_alg: Crypto wrappers for Linux kernel crypto (AF_ALG)

af_alg: Crypto wrappers for Linux kernel crypto (AF_ALG)

CONFIG_TLS=linux can now be used to select the crypto implementation
that uses the user space socket interface (AF_ALG) for the Linux kernel
crypto implementation. This commit includes some of the cipher, hash,
and HMAC functions. The functions that are not available through AF_ALG
(e.g., the actual TLS implementation) use the internal implementation
(CONFIG_TLS=internal).

Signed-off-by: Jouni Malinen <j@w1.fi>