drm/modes: Avoid divide by zero harder in drm_mode_vrefresh()

drm_mode_vrefresh() is trying to avoid divide by zero
by checking whether htotal or vtotal are zero. But we may
still end up with a div-by-zero of vtotal*htotal*...

Cc: stable@vger.kernel.org
Reported-by:  <syzbot+622bba18029bcde672e1@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=622bba18029bcde672e1


Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241129042629.18280-2-ville.syrjala@linux.intel.com


Reviewed-by: Jani Nikula <jani.nikula@intel.com>