virtio: Handle irq 5.
virtio: Handle irq 5.

Bhyve assigns irq 5 to the virtio device, so add another workaround
until #32 is fixed.

Solo5/solo5,djwillia/solo5,mato/solo5,djwillia/solo5,mato/solo5,djwillia/solo5,Weichen81/solo5,mato/solo5,Solo5/solo5,Weichen81/solo5,Weichen81/solo5