Add an overlay to reset the uboot bootcount

It is installed only on apt style images using uboot.
It uses tmpfiles.d

Signed-off-by: Frédéric Dalleau <frederic.dalleau@collabora.com>

apertis-image-uboot.yaml

@@ -25,6 +25,9 @@ actions:
     file: {{ $ospack }}.tar.gz
 {{- end }}
 
+  - action: overlay
+    source: overlays/reset-uboot-bootcount
+
   # Add multimedia demo pack
   # Provide URL via '-t demopack:"https://images.apertis.org/media/multimedia-demo.tar.gz"'
   # to add multimedia demo files

overlays/reset-uboot-bootcount/usr/lib/tmpfiles.d/reset-uboot-bootcount.conf

+# tmpfiles.d snipped to reset the bootcount
+# /boot/uboot.cnt does not need to have any content
+# uboot finds the empty file, mentions the error and boots normally
+# The tmpfiles.d overwrites whatever u-boot will have written
+F   /boot/uboot.cnt - - - -