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.cpp b/services/surfaceflinger/DisplayHardware/FramebufferSurface.cpp
index 7557e3f..960f9a9 100644
--- a/services/surfaceflinger/DisplayHardware/FramebufferSurface.cpp
+++ b/services/surfaceflinger/DisplayHardware/FramebufferSurface.cpp
@@ -134,7 +134,7 @@
     if (fenceFd >= 0) {
         sp<Fence> fence(new Fence(fenceFd));
         if (mCurrentBufferSlot != BufferQueue::INVALID_BUFFER_SLOT) {
-            status_t err = addReleaseFence(mCurrentBufferSlot, fence);
+            err = addReleaseFence(mCurrentBufferSlot, fence);
             ALOGE_IF(err, "setReleaseFenceFd: failed to add the fence: %s (%d)",
                     strerror(-err), err);
         }
@@ -142,21 +142,22 @@
     return err;
 }
 
-status_t FramebufferSurface::setUpdateRectangle(const Rect& r)
-{
-    return INVALID_OPERATION;
-}
-
 status_t FramebufferSurface::compositionComplete()
 {
     return mHwc.fbCompositionComplete();
 }
 
 void FramebufferSurface::dump(String8& result) {
-    mHwc.fbDump(result);
     ConsumerBase::dump(result);
 }
 
+void FramebufferSurface::dumpLocked(String8& result, const char* prefix,
+            char* buffer, size_t SIZE) const
+{
+    mHwc.fbDump(result);
+    ConsumerBase::dumpLocked(result, prefix, buffer, SIZE);
+}
+
 // ----------------------------------------------------------------------------
 }; // namespace android
 // ----------------------------------------------------------------------------