net: tcp: remove call to obsolete crypto_ahash_alignmask()

linux-next hit the following build error:

net/ipv4/tcp_ao.c: In function 'tcp_ao_key_alloc':
net/ipv4/tcp_ao.c:1536:13: error: implicit declaration of function 'crypto_ahash_alignmask'; did you mean 'crypto_ahash_alg_name'? [-Werror=implicit-function-declaration]
 1536 |         if (crypto_ahash_alignmask(tfm) > TCP_AO_KEY_ALIGN) {
      |             ^~~~~~~~~~~~~~~~~~~~~~
      |             crypto_ahash_alg_name

Caused by commit from the crypto tree

  0f8660c8 ("crypto: ahash - remove crypto_ahash_alignmask")

interacting with commit

  4954f17d

 ("net/tcp: Introduce TCP_AO setsockopt()s")

from networking. crypto_ahash_alignmask() has been phased out
by the former commit, drop the call in networking.
Eric confirms that the check is safe to remove and was questionable
here in the first place.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Reviewed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>