virsh_domif_setlink_getlink:Remove driver settings from iface when model is not virtio

[chloerh]

'driver' is only supported by virtio

Depends on:

• https://github.com/avocado-framework/avocado-vt/pull/3999

Test result:

(01/12) type_specific.io-github-autotest-libvirt.virsh.domif_setlink_getlink.positive_test.e1000e.interface_net.no_config.domain_name.running_guest.domif_setlink.setlink_down: PASS (82.74 s)
 (02/12) type_specific.io-github-autotest-libvirt.virsh.domif_setlink_getlink.positive_test.e1000e.interface_net.no_config.domain_name.running_guest.domif_setlink.stable_test.setlink_down.restart_libvirtd: PASS (193.15 s)
 (03/12) type_specific.io-github-autotest-libvirt.virsh.domif_setlink_getlink.positive_test.e1000e.interface_mac.no_config.domain_name.running_guest.domif_setlink.setlink_down: PASS (72.76 s)
 (04/12) type_specific.io-github-autotest-libvirt.virsh.domif_setlink_getlink.positive_test.e1000e.interface_mac.no_config.domain_name.running_guest.domif_setlink.stable_test.setlink_up.save_restore: PASS (82.62 s)
 (05/12) type_specific.io-github-autotest-libvirt.virsh.domif_setlink_getlink.positive_test.e1000e.interface_mac.no_config.domain_name.running_guest.domif_setlink.stable_test.setlink_down.save_restore:PAASS (184.97 s)
 (06/12) type_specific.io-github-autotest-libvirt.virsh.domif_setlink_getlink.positive_test.rtl8139.interface_net.no_config.domain_name.running_guest.domif_setlink.setlink_down: PASS (80.13 s)
 (07/12) type_specific.io-github-autotest-libvirt.virsh.domif_setlink_getlink.positive_test.rtl8139.interface_net.no_config.domain_name.running_guest.domif_setlink.stable_test.setlink_down.restart_libvirtd: PASS (190.98 s)
 (08/12) type_specific.io-github-autotest-libvirt.virsh.domif_setlink_getlink.positive_test.rtl8139.interface_mac.no_config.domain_name.running_guest.domif_setlink.setlink_down: PASS (78.10 s)
 (09/12) type_specific.io-github-autotest-libvirt.virsh.domif_setlink_getlink.positive_test.rtl8139.interface_mac.no_config.domain_name.running_guest.domif_setlink.stable_test.setlink_up.save_restore: PASS (84.44 s)
 (10/12) type_specific.io-github-autotest-libvirt.virsh.domif_setlink_getlink.positive_test.rtl8139.interface_mac.no_config.domain_name.running_guest.domif_setlink.stable_test.setlink_down.save_restore:PASS (185.93 s)
 (11/12) type_specific.io-github-autotest-libvirt.virsh.domif_setlink_getlink.multi_functional_test.e1000e.check_update_device: PASS (90.11 s)
 (12/12) type_specific.io-github-autotest-libvirt.virsh.domif_setlink_getlink.multi_functional_test.rtl8139.check_update_device: PASS (87.60 s)
RESULTS    : PASS 12 | ERROR 0 | FAIL 0 | SKIP 0 | WARN 0 | INTERRUPT 0 | CANCEL 0