dev-virtio: don't set the 9p default root

It is better to force users to explicitly set this argument, since
it is unlikely that we will find one safe option for all users.

Change-Id: I612520a44efd205a029a40cd13402584d16e1d88
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/22828
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
1 file changed