abootimg/mkboot/mkbootimg classes: Use the newer KERNEL_IMAGE_NAME instead of KERNEL_IMAGE_BASE_NAME and KERNEL_IMAGE_LINK_NAME instead of KERNEL_IMAGE_SYMLINK_NAME on thud

abootimg, mkbootimg, mkboot, statefs, timed: Use the new pkg_postinst_ontarget syntax of OE sumo instead of the previously used failing pkg_postinst