Reinstate all missing os-release fields

These fields are read by Balena when registering a device in the cloud.
Balena depends on the default os-release.bb recipe which adds these
fields. Balena then appens their own fields to the list. However, the
Kontron BSP overrides the list of fields to include. Therefor, we
reinstate the missing ones in our meta-balena-kontron layer.

layers/meta-balena-kontron/recipes-core/os-release/os-release.bbappend

@@ -1 +1,2 @@
-OS_RELEASE_FIELDS:append = " PRETTY_NAME"
+# Reinstate the fields present in Poky but not in meta-ked-bsp
+OS_RELEASE_FIELDS:append = " PRETTY_NAME ID_LIKE VERSION_ID PRETTY_NAME DISTRO_CODENAME"