Generate SHA512 hashes for build packages

- Aptly generates SHA512 hashes, but Rapture did not. Missing SHA512
hashes seem to cause hash mismatch failures between the local and remote
apt when installing them into the rootfs.

Change-Id: I4512c3026d611a48fa2c107ce67e4afc9398ec38
diff --git a/update_packages.sh b/update_packages.sh
index 1f3f399..667cd5c 100755
--- a/update_packages.sh
+++ b/update_packages.sh
@@ -16,6 +16,6 @@
 
 (
 	flock -e 200
-	( cd $PRODUCT_OUT/packages; apt-ftparchive -o APT::FTPArchive::SHA512=false packages bsp > Packages )
-	( cd $PRODUCT_OUT/packages; apt-ftparchive -o APT::FTPArchive::SHA512=false packages core >> Packages )
+	( cd $PRODUCT_OUT/packages; apt-ftparchive packages bsp > Packages )
+	( cd $PRODUCT_OUT/packages; apt-ftparchive packages core >> Packages )
 ) 200>$PRODUCT_OUT/obj/packages-lock