crypto: arm64/aes-xts-ce: fix for big endian

Emit the XTS tweak literal constants in the appropriate order for a
single 128-bit scalar literal load.

Fixes: 49788fe2

 ("arm64/crypto: AES-ECB/CBC/CTR/XTS using ARMv8 NEON and Crypto Extensions")
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>