crypto: artpec6 - Remove VLA usage of skcipher

crypto: artpec6 - Remove VLA usage of skcipher

In the quest to remove all stack VLA usage from the kernel[1], this
replaces struct crypto_skcipher and SKCIPHER_REQUEST_ON_STACK() usage
with struct crypto_sync_skcipher and SYNC_SKCIPHER_REQUEST_ON_STACK(),
which uses a fixed stack size.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com

Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Lars Persson <lars.persson@axis.com>
Cc: linux-arm-kernel@axis.com
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Lars Persson <lars.persson@axis.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>