Revert "Move algorithm specific ppccap code from crypto/ppccap.c"

Now that we can link specifically with static libraries, the immediate
need to split ppccap.c (and eventually other *cap.c files) is no more.

This reverts commit e3fb4d3d52e188b83ccb8506aa2f16cb686f4d6c.

Reviewed-by: Rich Salz <rsalz@openssl.org>