crypto: x86/aesni - convert to use AEAD SIMD helpers

Convert the AES-NI implementations of "gcm(aes)" and "rfc4106(gcm(aes))"
to use the AEAD SIMD helpers, rather than hand-rolling the same
functionality.  This simplifies the code and also fixes the bug where
the user-provided aead_request is modified.

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