AK2+Backend: tidy up remaining intentional stderr

- no need to see these when there is an expected error during normal use

META-INF/com/google/android/update-binary

@@ -48,9 +48,9 @@ ui_print "$(file_getprop /tmp/anykernel/anykernel.sh kernel.string)";
 ui_print " ";
 ui_print "AnyKernel2 by osm0sis @ xda-developers";
 ui_print " ";
-umount /system;
+umount /system 2>/dev/null;
 mount -o ro -t auto /system;
-mount /data;
+mount /data 2>/dev/null;
 test -f /system/system/build.prop && root=/system;
 
 if [ "$(file_getprop /tmp/anykernel/anykernel.sh do.devicecheck)" == 1 ]; then

tools/ak2-core.sh

@@ -208,7 +208,7 @@ write_boot() {
     $bin/flash_erase $block 0 0;
     $bin/nandwrite -p $block /tmp/anykernel/boot-new.img;
   else
-    dd if=/dev/zero of=$block;
+    dd if=/dev/zero of=$block 2>/dev/null;
     dd if=/tmp/anykernel/boot-new.img of=$block;
   fi;
 }