[CRYPTO] Handle unaligned iv from encrypt_iv/decrypt_iv

Even though cit_iv is now always aligned, the user can still supply an
unaligned iv through crypto_cipher_encrypt_iv/crypto_cipher_decrypt_iv.
This patch will check the alignment of the user-supplied iv and copy
it if necessary.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>