agl-kvm-demo-platform does not build for h3ulcb-kf

Reported on the mailing list:

https://lists.automotivelinux.org/g/agl-dev-community/message/10497

While the agl-kvm feature and agl-kvm-demo-platform image combination has not previously been tested on anything other than the reference hardware (i.e. h3ulcb machine with agl-refhw-h3 feature), the effort to support building for the other aarch64 platforms, especially the other H3 variants, is likely reasonable.  There will be outstanding issues with respect to QEMU configuration for the KVM guests for boards other than the reference hardware, but being able to build the image is a starting point to someone working out a solution for those.