CVE-2024-47704

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

drm/amd/display: Check link_res->hpo_dp_link_enc before using it

[WHAT & HOW]
Functions dp_enable_link_phy and dp_disable_link_phy can pass link_res
without initializing hpo_dp_link_enc and it is necessary to check for
null before dereferencing.

This fixes 2 FORWARD_NULL issues reported by Coverity.