drm_hwcomposer: Add HDMI connector as a valid type

Accept DRM_MODE_CONNECTOR_HDMIA connector type.

Look for primary DrmConnector amongst external connectors
after looking for primary amongst internal ones first.

Signed-off-by: Robert Foss <robert.foss@collabora.com>
Signed-off-by: Rob Herring <robh@kernel.org>
diff --git a/drmconnector.h b/drmconnector.h
index e1488bb..5601e06 100644
--- a/drmconnector.h
+++ b/drmconnector.h
@@ -44,7 +44,9 @@
   int display() const;
   void set_display(int display);
 
-  bool built_in() const;
+  bool internal() const;
+  bool external() const;
+  bool valid_type() const;
 
   int UpdateModes();