Revert "hype: support upgrade of rootfs on live systems when placing new rootfs.img.update alongside rootfs.img and rebooting."

This reverts commit 5418a968763b054423afdbeeb81751271a8aaf9c.
kernel: support built-in xen-pciback to support boot-time arguments.
xen recipe: add build support for qemu-xen-traditional as optional separate package xen-qemu and a fix to build seabios.
hype-rootfs: include both upstream qemu and xen-qemu in rootfs.