Minor cleanups/fixes before virtual display refactoring

None of these should change behavior, except for removing some
incorrect log messages when using a virtual display.

- HWComposer::getAndResetReleaseFenceFd() checks the HWC version, so
  no need to do that in the DisplayDevice::onSwapBuffersCompleted().
  However, it should check that mFramebufferSurface is not NULL like
  it is for virtual displays.
- Comment that FramebufferSurface::dump() overrides the non-virtual
  ConsumerBase::dump(), and fix it so the right thing happens
  regardless of the static type of the pointer/reference the callee
  has. FramebufferSurface::dump() could be removed right now, but I'd
  need to bring it back in a later change.
- Use the right enum for validating display type ids.
- Don't try to send hotplug events for virtual displays.
- Mark virtual displays as connected so HWComposer::prepare() doesn't
  think something is wrong when it gets a non-NULL layer list.
- Remove unused FramebufferSurface methods.

Bug: 8384764
Change-Id: Id28a2f9be86b45f4bb7915fdf7752157035f4294
diff --git a/services/surfaceflinger/DisplayHardware/FramebufferSurface.h b/services/surfaceflinger/DisplayHardware/FramebufferSurface.h
index b61b7f5..639e720 100644
--- a/services/surfaceflinger/DisplayHardware/FramebufferSurface.h
+++ b/services/surfaceflinger/DisplayHardware/FramebufferSurface.h
@@ -36,11 +36,11 @@
 public:
     FramebufferSurface(HWComposer& hwc, int disp);
 
-    bool isUpdateOnDemand() const { return false; }
-    status_t setUpdateRectangle(const Rect& updateRect);
     status_t compositionComplete();
 
-    virtual void dump(String8& result);
+    // TODO(jessehall): This overrides the non-virtual ConsumerBase version.
+    // Will rework slightly in a following change.
+    void dump(String8& result);
 
     // setReleaseFenceFd stores a fence file descriptor that will signal when the
     // current buffer is no longer being read. This fence will be returned to
@@ -56,6 +56,9 @@
     virtual void onFrameAvailable();
     virtual void freeBufferLocked(int slotIndex);
 
+    virtual void dumpLocked(String8& result, const char* prefix,
+            char* buffer, size_t SIZE) const;
+
     // nextBuffer waits for and then latches the next buffer from the
     // BufferQueue and releases the previously latched buffer to the
     // BufferQueue.  The new buffer is returned in the 'buffer' argument.