[syzbot] [dri?] divide error in drm_mode_vrefresh

[syzbot]

Hello,

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

Reported-and-tested-by: syzbot+622bba18029bcde672e1 at syzkaller.appspotmail.com

Tested on:

commit:         1c7873e3 mm: lock newly mapped VMA with corrected orde..
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=101196d2a80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8f6b0c7ae2c9c303
dashboard link: https://syzkaller.appspot.com/bug?extid=622bba18029bcde672e1
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
patch:          https://syzkaller.appspot.com/x/patch.diff?x=10e44354a80000

Note: testing is done by a robot and is best-effort only.