drm/amd/display: Skip on writeback when it's not applicable

In the Linux kernel, the following vulnerability has been resolved: drm/amd/display: Skip on writeback when it's not applicable [WHY] dynamic memory safety error detector (KASAN) catches and generates error messages "BUG: KASAN: slab-out-of-bounds" as writeback connector does not support certain features which are not initialized. [HOW] Skip them when connector type is DRM_MODE_CONNECTOR_WRITEBACK.