Make virtio queue re-initialization steps to be similar to
original initialization, so we don't miss few registers to
configure.

This fixes vtnet(4) operation with QEMU's virtio-net-device.

Tested in QEMU with FreeBSD/RISC-V.

Reviewed by: bryanv
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D15821