virttest.qemu_devices: Support aliases in has_device

Signed-off-by: Lukáš Doktor <ldoktor@redhat.com>
virttest.qemu_vm: Utilize aliases support in add_pcidevice

qemu_devices support aliases so we can just ask for the desired device.

Signed-off-by: Lukáš Doktor <ldoktor@redhat.com>
virttest.qemu_vm: add_pcidevice bugfixes

* check params of the desired device_driver instead of pci-assign
* log the fail_params instead of the last used param

Signed-off-by: Lukáš Doktor <ldoktor@redhat.com>
Merge pull request #1494 from ldoktor/framework2

virttest.qemu_devices: Support for aliases