CVE-2026-31460

In the Linux kernel, the following vulnerability has been resolved:

drm/amd/display: check if ext_caps is valid in BL setup

LVDS connectors don't have extended backlight caps so check
if the pointer is valid before accessing it.

(cherry picked from commit 3f797396d7f4eb9bb6eded184bbc6f033628a6f6)