UBUNTU-CVE-2024-49916: Null Pointer Dereference

In the Linux kernel, the following vulnerability has been resolved: drm/amd/display: Add NULL check for clkmgr and clkmgr->funcs in dcn401inithw This commit addresses a potential null pointer dereference issue in the dcn401inithw function. The issue could occur when dc->clkmgr or dc->clkmgr->funcs is null. The fix adds a check to ensure dc->clkmgr and dc->clkmgr->funcs is not null before accessing its functions. This prevents a potential null pointer dereference. Reported by smatch: drivers/gpu/drm/amd/amdgpu/../display/dc/hwss/dcn401/dcn401hwseq.c:416 dcn401inithw() error: we previously assumed 'dc->clkmgr' could be null (see line 225)