Patch adds 3-way parallel x86_64 assembly implementation of twofish as new
module. New assembler functions crypt data in three blocks chunks, improving
cipher performance on out-of-order CPUs.

Patch has been tested with tcrypt and automated filesystem tests.

Summary of the tcrypt benchmarks:

Twofish 3-way-asm vs twofish asm (128bit 8kb block ECB)
 encrypt: 1.3x speed
 decrypt: 1.3x speed

Twofish 3-way-asm vs twofish asm (128bit 8kb block CBC)
 encrypt: 1.07x speed
 decrypt: 1.4x speed

Twofish 3-way-asm vs twofish asm (128bit 8kb block CTR)
 encrypt: 1.4x speed

Twofish 3-way-asm vs AES asm (128bit 8kb block ECB)
 encrypt: 1.0x speed
 decrypt: 1.0x speed

Twofish 3-way-asm vs AES asm (128bit 8kb block CBC)
 encrypt: 0.84x speed
 decrypt: 1.09x speed

Twofish 3-way-asm vs AES asm (128bit 8kb block CTR)
 encrypt: 1.15x speed

Full output:
 http://koti.mbnet.fi/axh/kernel/crypto/tcrypt-speed-twofish-3way-asm-x86_64.txt
 http://koti.mbnet.fi/axh/kernel/crypto/tcrypt-speed-twofish-asm-x86_64.txt
 http://koti.mbnet.fi/axh/kernel/crypto/tcrypt-speed-aes-asm-x86_64.txt

Tests were run on:
 vendor_id  : AuthenticAMD
 cpu family : 16
 model      : 10
 model name : AMD Phenom(tm) II X6 1055T Processor

Also userspace test were run on:
 vendor_id  : GenuineIntel
 cpu family : 6
 model      : 15
 model name : Intel(R) Xeon(R) CPU           E7330  @ 2.40GHz
 stepping   : 11

Userspace test results:

Encryption/decryption of twofish 3-way vs x86_64-asm on AMD Phenom II:
 encrypt: 1.27x
 decrypt: 1.25x

Encryption/decryption of twofish 3-way vs x86_64-asm on Intel Xeon E7330:
 encrypt: 1.36x
 decrypt: 1.36x
Signed-off-by: NJussi Kivilinna <jussi.kivilinna@mbnet.fi>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>