riscv: qemu: Enable e1000 and nvme support

Since we have added the PCI support to the 'virt' target, enable
e1000 and NVME as alternate network and storage devices for these
virtio based devices.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Tested-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>