src/service: fix packing checksum.size into GVariant dict
src/service: fix packing checksum.size into GVariant dict

requires to be cast to packed type to be properly inserted.

Signed-off-by: Enrico Joerns <a2e5f936c390f36494e46e71bcfbe365bb1e8c49@pengutronix.de>

jluebbe/rauc,rauc/rauc,rauc/rauc,jluebbe/rauc,ejoerns/rauc,ejoerns/rauc,rauc/rauc,jluebbe/rauc,ejoerns/rauc