AK2: assume sha1 if "unknown" hash type encountered

- some Samsung device images can be unpacked and repacked with the standard tools but the id sha1 is offset differently than in the standard header resulting in broken hash type detection

tools/ak2-core.sh

@@ -59,6 +59,9 @@ dump_boot() {
     $bin/pxa1088-unpackbootimg -i /tmp/anykernel/boot.img -o $split_img;
   else
     $bin/unpackbootimg -i /tmp/anykernel/boot.img -o $split_img;
+    if [ "$(cat $split_img/boot.img-hash)" == "unknown" ]; then
+      echo "sha1" > $split_img/boot.img-hash;
+    fi;
   fi;
   if [ $? != 0 -o "$dumpfail" ]; then
     ui_print " "; ui_print "Dumping/splitting image failed. Aborting..."; exit 1;