drm/nouveau/disp/mcp7x: disable dptmds workaround

The workaround appears to cause regressions on these boards, and from
inspection of RM traces, NVIDIA don't appear to do it on them either.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Tested-by: Roy Spliet <nouveau@spliet.org>

drivers/gpu/drm/nouveau/nvkm/engine/disp/nv50.c

@@ -433,8 +433,6 @@ nv50_disp_dptmds_war(struct nvkm_device *device)
 	case 0x94:
 	case 0x96:
 	case 0x98:
-	case 0xaa:
-	case 0xac:
 		return true;
 	default:
 		break;