Revert "virtio: improve virtio devices initialization time"

Revert "virtio: improve virtio devices initialization time"

This reverts commit 6f0bb230722931d17fb284eee8efd40b9d653822.

This reverts commit f87d72f5c5bff0837d409a56bd34f439a90119ca as that is
reported to break cleanup and migration.

Cc: Gal Hammer <[email protected]>
Cc: Sitong Liu <[email protected]>
Cc: Xiaoling Gao <[email protected]>
Suggested-by: Greg Kurz <[email protected]>
Suggested-by: Paolo Bonzini <[email protected]>
Reported-by: Jose Ricardo Ziviani <[email protected]>
Reported-by: Daniel Henrique Barboza <[email protected]>