configs/qemu: drop arm nuri

This config has no prospect of going into the future (by using DTS), and
qemu doesn't do a good job at emulating it (networking problems), so
drop it.
All of the ARM SMP testing duties are now in the vexpress defconfig
which is better suited/supported.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>