CVE-2024-43886 drm/amd/display: Add null check in resource_log_pipe_topology_update

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

drm/amd/display: Add null check in resource_log_pipe_topology_update

[WHY]
When switching from “Extend” to “Second Display Only” we sometimes
call resource_get_otg_master_for_stream on a stream for the eDP,
which is disconnected. This leads to a null pointer dereference.

[HOW]
Added a null check in dc_resource.c/resource_log_pipe_topology_update.