drm/amd/display: Drop unused privacy_mask setters and getters

[Why and How]
dwbc_funcs.set/get_privacy_mask isn't being used anymore, drop it
Reviewed-by: Charlene Liu <Charlene.Liu@amd.com>
Acked-by: Alan Liu <HaoPing.Liu@amd.com>
Signed-off-by: Oliver Logush <oliver.logush@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/inc/hw/dwb.h

@@ -219,12 +219,6 @@ struct dwbc_funcs {
 		struct dwbc *dwbc,
 		const struct dc_transfer_func *in_transfer_func_dwb_ogam);
 
-	void (*get_privacy_mask)(
-		struct dwbc *dwbc, uint32_t *mask_id);
-
-	void (*set_privacy_mask)(
-		struct dwbc *dwbc, uint32_t mask_id);
-
 	//TODO: merge with output_transfer_func?
 	bool (*dwb_ogam_set_input_transfer_func)(
 		struct dwbc *dwbc,