Determine displayType in SurfaceFlinger

This change eliminates an assumption that the first hotplug connect
event is for the primary display, and all other events are for the
external display.

Bug: 38464421
Test: Boots, settings app navigable
Change-Id: I753deb9a4e99a7b225ab89562c7acf4ce284dbf5
diff --git a/services/surfaceflinger/DisplayHardware/HWC2.h b/services/surfaceflinger/DisplayHardware/HWC2.h
index a15c6d9..7b98b3e 100644
--- a/services/surfaceflinger/DisplayHardware/HWC2.h
+++ b/services/surfaceflinger/DisplayHardware/HWC2.h
@@ -65,8 +65,7 @@
 class ComposerCallback {
  public:
     virtual void onHotplugReceived(int32_t sequenceId, hwc2_display_t display,
-                                   Connection connection,
-                                   bool primaryDisplay) = 0;
+                                   Connection connection) = 0;
     virtual void onRefreshReceived(int32_t sequenceId,
                                    hwc2_display_t display) = 0;
     virtual void onVsyncReceived(int32_t sequenceId, hwc2_display_t display,