reforis: simplify Makefile
Reordered stuff in Makefile
Removed: PKG_BUILD_DIR, PKG_UNPACK, duplicated mention about maintainer
Added: PKG_LICENSE_FILES
Corrected License SPDX Identifier
cc: @bbodnar
Compile tested: TO, branch hbk
and verified that the content of both packages (the previous one and this one) are same.