drm/amd/display: Rename fs_params to hdr_tm_params

[Why&How]
Renaming structure to better indicate its meaning.

Signed-off-by: Krunoslav Kovac <Krunoslav.Kovac@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Anson Jacob <Anson.Jacob@amd.com>
Acked-by: Anthony Koo <Anthony.Koo@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>