virtio: finalize features before using device

virtio: finalize features before using device

Under the standard of Virtio 1.0, the initialization process of the
device must first write sub-features back to device before
using device, such as finding vqs.

There are four places using vp_find_vq().

1. virtio-blk.pci:    put the code of finalizing features in front of using device
2. virtio-blk.mmio:   put the code of finalizing features in front of using device
3. virtio-scsi.pci:   is ok
4. virtio-scsi.mmio:  add the code of finalizing features before vp_find_vq()

Link: https://www.mail-archive.com/qemu-devel@nongnu.org/msg920776.html
Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <20221114035818.109511-3-xuanzhuo@linux.alibaba.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>