crypto: x86 - remove assignments of 0 to cra_alignmask

Struct fields are zero by default, so these lines of code have no
effect.  Remove them to reduce the number of matches that are found when
grepping for cra_alignmask.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>