inmates: x86: Add E1000-based PCI DMA demonstration

This adds a simple Ethernet ping-ping via Intel E1000-based NICs. Run
two instances in the same network, and the first will become the test
controller while the second instance to show up will be the target.
Round trip times will be measured and dumped by the controller. This can
surely be further improved, and there are still some stability issues
(measurement stops on lost packet). It's a start.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
configs: qemu: put floppy IO ports into config

The qemu VM will have a floppy drive and we can not tell Qemu to not
emulate one. Now if the guest kernel has a driver for a floppy drive we
can get violations on "jailhouse enable". Of the shelf distro kernels
will have floppy support so we need to whitelist the floppy ports in the
qemu root cell config.

Signed-off-by: Henning Schild <henning.schild@siemens.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
README: Update after recent build system changes

This reflects the changes on KDIR (e2cc88642d) as well as the tool build
and installation (932db6709b).

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>