crypto: x86/aesni - Rearrange AES key size check

aes_expandkey() already includes an AES key size check. If AES-NI is
unusable, invoke the function without the size check.

Also, use aes_check_keylen() instead of open code.

Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: linux-crypto@vger.kernel.org
Cc: x86@kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>