Add some C64x assembly modules [by minor adjustments of C64x+ modules].

AES, SHA256 and SHA512 modules can actually replace corresponding
C64x+ modules. This is because C64x+ instructions don't actually
provide "killer-argument" advantage in these modules. As for SHA1,
even though its performance exactly same, C64x+ module is more
responsive to interrupts, i.e. doesn't inhibit them for as long
periods as C64x module.

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Stephen Henson <steve@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4265)

(cherry picked from commit 5526e579)