tests/libqos: add riscv/virt machine nodes

tests/libqos: add riscv/virt machine nodes

Add a RISC-V 'virt' machine to the graph. This implementation is a
modified copy of the existing arm machine in arm-virt-machine.c

It contains a virtio-mmio and a generic-pcihost controller. The
generic-pcihost controller hardcodes assumptions from the ARM 'virt'
machine, like ecam and pio_base addresses, so we'll add an extra step to
set its parameters after creating it.

Our command line is incremented with 'aclint' parameters to allow the
machine to run MSI tests.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Acked-by: Thomas Huth <thuth@redhat.com>
Message-ID: <20240217192607.32565-7-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>