crypto: ccm - drop unnecessary minimum 32-bit alignment

The CCM driver forces 32-bit alignment even if the underlying ciphers
don't care about alignment. This is because crypto_xor() used to require
this, but since this is no longer the case, drop the hardcoded minimum
of 32 bits.

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