intel_extreme: only access ports pipe if it has one assigned.

src/add-ons/accelerants/intel_extreme/Ports.cpp

@@ -163,6 +163,11 @@ Port::SetPipe(Pipe* pipe)
 status_t
 Port::Power(bool enabled)
 {
+	if (fPipe == NULL) {
+		ERROR("%s: Setting power mode without assigned pipe!\n", __func__);
+		return B_ERROR;
+	}
+
 	fPipe->Enable(enabled);
 
 	return B_OK;

src/add-ons/accelerants/intel_extreme/dpms.cpp

@@ -32,6 +32,8 @@ enable_all_pipes(bool enable)
 			continue;
 		if (!gInfo->ports[i]->IsConnected())
 			continue;
+		if (gInfo->ports[i]->GetPipe() == NULL)
+			continue;
 
 		gInfo->ports[i]->Power(enable);
 	}