crypto: vmac - don't set alignmask

The vmac template is setting its alignmask to that of its underlying
'cipher'.  This doesn't actually accomplish anything useful, though, so
stop doing it.  (vmac_update() does have an alignment bug, where it
assumes u64 alignment when it shouldn't, but that bug exists both before
and after this patch.)  This is a prerequisite for removing support for
nonzero alignmasks from shash.

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