virtio_page_per_vq: enhance input event file

[dzhengfy]

Regarding /dev/input/event* files, there might be some different situation.
For example,

• No event file exsit at all
• Only /dev/input/event0 exists
• Only /dev/input/event1 exists
• Both /dev/input/event0 and /dev/input/event1 exists
• and more ...

So this patch is intending to support above situations instead of hardcoding with event1.

[dzhengfy]

Without the fix:

[rhel.virtio_attributes.virtio_page_per_vq.input.passthrough.default_start]
VMStartError: VM 'avocado-vt-vm1' failed to start: error: Failed to start domain 'avocado-vt-vm1'error: Path '/dev/input/event1' is not accessible: No such file or directory(exit status: 1)


Test on arm libvirt-10.5.0-6:

When no event file:
(1/1) type_specific.io-github-autotest-libvirt.virtio_attributes.virtio_page_per_vq.input.passthrough.hotplug: CANCEL: ls: cannot access '/dev/input/event*': No such file or directory\n (8.53 s)
RESULTS : PASS 0 | ERROR 0 | FAIL 0 | SKIP 0 | WARN 0 | INTERRUPT 0 | CANCEL 1
JOB HTML : /var/log/avocado/job-results/job-2024-09-06T05.07-6f4fdfa/results.html
JOB TIME : 9.11 s

When /dev/input/event0 exists:
(1/1) type_specific.io-github-autotest-libvirt.virtio_attributes.virtio_page_per_vq.input.passthrough.hotplug: PASS (41.30 s)
RESULTS : PASS 1 | ERROR 0 | FAIL 0 | SKIP 0 | WARN 0 | INTERRUPT 0 | CANCEL 0
JOB HTML : /var/log/avocado/job-results/job-2024-09-06T04.55-1440a9c/results.html
JOB TIME : 41.88 s

(1/1) type_specific.io-github-autotest-libvirt.virtio_attributes.virtio_page_per_vq.input.passthrough.default_start: PASS (34.80 s)

[yafu-1]

LGTM

[chloerh]

Oh, conflicting