crypto: fpu - Add template for blkcipher touching FPU

Blkcipher touching FPU need to be enclosed by kernel_fpu_begin() and
kernel_fpu_end(). If they are invoked in cipher algorithm
implementation, they will be invoked for each block, so that
performance will be hurt, because they are "slow" operations. This
patch implements "fpu" template, which makes these operations to be
invoked for each request.

Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>