crypto: geode-aes - convert to skcipher API and make thread-safe

The geode AES driver is heavily broken because it stores per-request
state in the transform context.  So it will crash or produce the wrong
result if used by any of the many places in the kernel that issue
concurrent requests for the same transform object.

This driver is also implemented using the deprecated blkcipher API,
which makes it difficult to fix, and puts it among the drivers
preventing that API from being removed.

Convert this driver to use the skcipher API, and change it to not store
per-request state in the transform context.

Fixes: 9fe757b0 ("[PATCH] crypto: Add support for the Geode LX AES hardware")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>