Removed original sha2 and made code use sph_sha2

We don't need redundant SHA2 code nor duplicate filenames.
This is subject for discussion and testing (Linux, MinGW).

(algorithm.c spaces/indentation fixed, too)

btw, since you already have this line, it would be better to change below 2 lines to 2* sph_sha256/sph_sha256_close. Since this will reuse the same context.