drm/amd/display: Fix dmub_cmd header alignment

[why & how]
Header misalignment in struct dmub_cmd_replay_copy_settings_data and
struct dmub_alpm_auxless_data causes incorrect data read between driver
and dmub.
Fix the misalignment and ensure that everything is aligned to 4-byte
boundaries.

Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Ovidiu Bunea <ovidiu.bunea@amd.com>
Signed-off-by: Ivan Lipski <ivan.lipski@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>