fix Makefile chmod (644)
replace MD5SUM with HASH
add PKG_MIRROR_HASH when PKG_SOURCE_PROTO:=git

(PKG_SOURCE_PROTO:=svn tarballs are not reproducible for now)

Signed-off-by: Etienne Champetier <champetier.etienne@gmail.com>

libsoc is a C library for interfacing with common SoC
peripherals through generic kernel interfaces. This
library is already part of Buildroot and OpenEmbedded.

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>