[syzbot] [dri?] WARNING in vkms_get_vblank_timestamp

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+75cc0f9f7e6324dd2501 at syzkaller.appspotmail.com

Tested on:

commit:         7d8214bb Add linux-next specific files for 20230412
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1387763dc80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=923e20c1867d7c1c
dashboard link: https://syzkaller.appspot.com/bug?extid=75cc0f9f7e6324dd2501
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Note: no patches were applied.
Note: testing is done by a robot and is best-effort only.