merge the different ExampleTop subclasses into the example package

src/main/scala/example/Top.scala

@@ -24,3 +24,20 @@ class ExampleTopModule[+L <: ExampleTop](l: L) extends BaseSystemModule(l)
     with HasRocketPlexMasterModuleImp
     with HasNoDebugModuleImp
     with HasPeripherySerialModuleImp
+
+class ExampleTopWithPWM(implicit p: Parameters) extends ExampleTop
+    with HasPeripheryPWM {
+  override lazy val module = new ExampleTopWithPWMModule(this)
+}
+
+class ExampleTopWithPWMModule(l: ExampleTopWithPWM)
+  extends ExampleTopModule(l) with HasPeripheryPWMModuleImp
+
+class ExampleTopWithBlockDevice(implicit p: Parameters) extends ExampleTop
+    with HasPeripheryBlockDevice {
+  override lazy val module = new ExampleTopWithBlockDeviceModule(this)
+}
+
+class ExampleTopWithBlockDeviceModule(l: ExampleTopWithBlockDevice)
+  extends ExampleTopModule(l)
+  with HasPeripheryBlockDeviceModuleImp