[Description]
- Add logging for first DMUB inbox message that timed out to diagnostic
  data
- It is useful to track the first failed message for debug purposes
  because once DMUB becomes hung (typically on a message), it will
  remain hung and all subsequent messages. In these cases we're
  interested in knowing which is the first message that failed.
Reviewed-by: Josip Pavic <josip.pavic@amd.com>
Acked-by: Roman Li <roman.li@amd.com>
Signed-off-by: Alvin Lee <alvin.lee2@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>