crypto: stm32 - remove unnecessary alignmask for ahashes

The crypto API's support for alignmasks for ahash algorithms is nearly
useless, as its only effect is to cause the API to align the key and
result buffers.  The drivers that happen to be specifying an alignmask
for ahash rarely actually need it.  When they do, it's easily fixable,
especially considering that these buffers cannot be used for DMA.

In preparation for removing alignmask support from ahash, this patch
makes the stm32 driver no longer use it.  This driver didn't actually
rely on it; it only writes to the result buffer in stm32_hash_finish(),
simply using memcpy().  And stm32_hash_setkey() does not assume any
alignment for the key buffer.

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