Makefile Specifications: update targets for SHA2_256 & SHA2_512
Makefile Specifications: update targets for SHA2_256 & SHA2_512

mitls/hacl-star,mitls/hacl-star,mitls/hacl-star,mitls/hacl-star,mitls/hacl-star,mitls/hacl-star,mitls/hacl-star,mitls/hacl-star,mitls/hacl-star