crypto: x86 - restore avx2_supported check

Commit 3d387ef0 (Revert "crypto: blowfish - add AVX2/x86_64 implementation
of blowfish cipher") reverted too much as it removed the 'assembler supports
AVX2' check and therefore disabled remaining AVX2 implementations of Camellia
and Serpent. Patch restores the check and enables these implementations.

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