CVE-2025-38361 drm/amd/display: Check dce_hwseq before dereferencing it

In the Linux kernel, the following vulnerability has been resolved: drm/amd/display: Check dcehwseq before dereferencing it WHAT hws was checked for null earlier in dce110blankstream, indicating hws can be null, and should be checked whenever it is used. cherry picked from commit...