target-arm: crypto: fix BE host support

The crypto emulation code in target-arm/crypto_helper.c never worked
correctly on big endian hosts, due to the fact that it uses a union
of array types to convert between the native VFP register size (64
bits) and the types used in the algorithms (bytes and 32 bit words)

We cannot just swab between LE and BE when reading and writing the
registers, as the SHA code performs word additions, so instead, add
array accessors for the CRYPTO_STATE type whose LE and BE specific
implementations ensure that the correct array elements are referenced.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Message-id: 1420208303-24111-1-git-send-email-ard.biesheuvel@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>