crypto: aes - create AES library based on the fixed time AES code

Take the existing small footprint and mostly time invariant C code
and turn it into a AES library that can be used for non-performance
critical, casual use of AES, and as a fallback for, e.g., SIMD code
that needs a secondary path that can be taken in contexts where the
SIMD unit is off limits (e.g., in hard interrupts taken from kernel
context)

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

lib/crypto/Makefile

@@ -1,4 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 
+obj-$(CONFIG_CRYPTO_LIB_AES) += libaes.o
+libaes-y := aes.o
+
 obj-$(CONFIG_CRYPTO_LIB_ARC4) += libarc4.o
 libarc4-y := arc4.o