qemu.tests.pci_devices: Get firmware time to initialize

Before "info qtree" returns the correct values, firmware initialization
has to finish. 10s should be enough (in case we won't define 1000
devices)

Signed-off-by: Lukáš Doktor <ldoktor@redhat.com>
qemu.tests.pci_devices: Add virtio_disk testing devices

This patch adds the possibility to use virtio_disks for testing.

Signed-off-by: Lukáš Doktor <ldoktor@redhat.com>
qemu.tests.pci_devices: Add support for uhci test device

Make it possible to use ich9-usb-uhci controller for pci_devices testing

Signed-off-by: Lukáš Doktor <ldoktor@redhat.com>
virttest.qemu_devices: Fix the bug with overwritten bus for virtio disk

The bus property of virtio disks is set by pci_bus and is set during
device insertion via parent_bus.

Signed-off-by: Lukáš Doktor <ldoktor@redhat.com>
qemu.tests.pci_devices: Major config update

Original setups were only for developing the test and some of them
were invalid (impossible for real hw and thus unsupported by kernel).
These setups were checked with pci device developer and they should be
working properly.
Merge pull request #1222 from ldoktor/add_device3

qemu.tests.pci_devices: Test fixup and update