drm/amd/display: Fix unused parameters warnings in dml2_0

drm/amd/display: Fix unused parameters warnings in dml2_0

[Why] Resolve warnings by marking unused parameters explicitly.

[How] Keep parameter names in signatures and add a line with
     '(void)param;'  inside the function body

Preserved function signatures and avoids breaking code paths that
may reference the parameter under conditional compilation.

Reviewed-by: Dillon Varone <dillon.varone@amd.com>
Reviewed-by: Clayton King <clayton.king@amd.com>
Signed-off-by: Gaghik Khachatrian <gaghik.khachatrian@amd.com>
Signed-off-by: Roman Li <roman.li@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>