Remove all traces of long obsolete OMXComponentBase class.

Change-Id: I749994fe1560363afc95beae45b66ea56a20caa8
diff --git a/include/media/hardware/OMXPluginBase.h b/include/media/hardware/OMXPluginBase.h
index 2fd8e12..7bf4147 100644
--- a/include/media/hardware/OMXPluginBase.h
+++ b/include/media/hardware/OMXPluginBase.h
@@ -27,8 +27,6 @@
 
 namespace android {
 
-struct OMXComponentBase;
-
 struct OMXPluginBase {
     OMXPluginBase() {}
     virtual ~OMXPluginBase() {}