Patch adds LRW support for serpent-sse2 by using lrw_crypt(). Patch has been
tested with tcrypt and automated filesystem tests.

Tcrypt benchmarks results (serpent-sse2/serpent_generic speed ratios):

Benchmark results with tcrypt:

Intel Celeron T1600 (x86_64) (fam:6, model:15, step:13):
size    lrw-enc lrw-dec
16B     1.00x   0.96x
64B     1.01x   1.01x
256B    3.01x   2.97x
1024B   3.39x   3.33x
8192B   3.35x   3.33x

AMD Phenom II 1055T (x86_64) (fam:16, model:10):
size    lrw-enc lrw-dec
16B     0.98x   1.03x
64B     1.01x   1.04x
256B    2.10x   2.14x
1024B   2.28x   2.33x
8192B   2.30x   2.33x

Intel Atom N270 (i586):
size    lrw-enc lrw-dec
16B     0.97x   0.97x
64B     1.47x   1.50x
256B    1.72x   1.69x
1024B   1.88x   1.81x
8192B   1.84x   1.79x

Signed-off-by: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>