CVE-2024-39498 drm/mst: Fix NULL pointer dereference at drm_dp_add_payload_part2

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

drm/mst: Fix NULL pointer dereference at drm_dp_add_payload_part2

[Why]
Commit:

• commit 5aa1dfcdf0a4 (“drm/mst: Refactor the flow for payload allocation/removement”)
  accidently overwrite the commit
• commit 54d217406afe (“drm: use mgr->dev in drm_dbg_kms in drm_dp_add_payload_part2”)
  which cause regression.

[How]
Recover the original NULL fix and remove the unnecessary input parameter ‘state’ for
drm_dp_add_payload_part2().

(cherry picked from commit 4545614c1d8da603e57b60dd66224d81b6ffc305)