virtio: find_vqs/del_vqs fixes

Here's a patch series to fix known regressions in virtio_pci, by refactoring code along the lines suggested by Rusty.

Changes since v3:
whitespace fixed in PATCH 1/2

This is on top of patch
virtio: fix memory leak on device removal
that has been applied by Rusty.

This supercedes patches:
[PATCHv3] virtio: recover from vector assignment failure [PATCHv2] virtio: fix double free_irq on device removal

Michael S. Tsirkin (2):
virtio: make del_vq delete vq from list
virtio: refactor find_vqs

 drivers/virtio/virtio_pci.c |  218 ++++++++++++++++++++++++-------------------
 1 files changed, 124 insertions(+), 94 deletions(-)