drm/amd/display: Add more debug data to dmub_srv

[Why]
When analyzing some crash dumps, not all of the expected DMUB info was
available, so we want to add in-object storage for this data.

[How]
 - dmub_srv_debug (renamed to dmub_timeout_info) is already a member of
dmub_diagnostic_data, therefore keep a dmub_diagnostic_data directly in
dmub_srv
 - use dmub_srv->debug when collecting diagnostic info instead of stack
object to allow for easy inspection in crash dumps

Reviewed-by: Alvin Lee <alvin.lee2@amd.com>
Signed-off-by: Joshua Aberback <joshua.aberback@amd.com>
Signed-off-by: Tom Chung <chiahsuan.chung@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>