Add implementation tuned for more performance on real hardware. Changes are
mostly around the part mixing 128-bit extract and insert instructions and
AES-NI instructions. Also 'vpbroadcastb' instructions have been change to
'vpshufb with zero mask'.

Tests on Intel Core i5-4570:

tcrypt ECB results, old-AVX2 vs new-AVX2:

size    128bit key      256bit key
        enc     dec     enc     dec
256     1.00x   1.00x   1.00x   1.00x
1k      1.08x   1.09x   1.05x   1.06x
8k      1.06x   1.06x   1.06x   1.06x

tcrypt ECB results, AVX vs new-AVX2:

size    128bit key      256bit key
        enc     dec     enc     dec
256     1.00x   1.00x   1.00x   1.00x
1k      1.51x   1.50x   1.52x   1.50x
8k      1.47x   1.48x   1.48x   1.48x
Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>