crypto: sha - SHA1 transform x86_64 AVX2

This git patch adds x86_64 AVX2 optimization of SHA1
transform to crypto support. The patch has been tested with 3.14.0-rc1
kernel.

On a Haswell desktop, with turbo disabled and all cpus running
at maximum frequency, tcrypt shows AVX2 performance improvement
from 3% for 256 bytes update to 16% for 1024 bytes update over
AVX implementation.

This patch adds sha1_avx2_transform(), the glue, build and
configuration changes needed for AVX2 optimization of
SHA1 transform to crypto support.

sha1-ssse3 is one module which adds the necessary optimization
support (SSSE3/AVX/AVX2) for the low-level SHA1 transform function.
With better optimization support, transform function is overridden
as the case may be. In the case of AVX2, due to performance reasons
across datablock sizes, the AVX or AVX2 transform function is used
at run-time as it suits best. The Makefile change therefore appends
the necessary objects to the linkage. Due to this, the patch merely
appends AVX2 trans...