Fix unused-parameter warnings

These are exposed when frameworks/av/include is moved from being a
system include directory to a normal include directory.

Test: m -j checkbuild
Change-Id: I0e3787fbee70339f7dcbc979f448800ecfff0f17
Merged-In: I0e3787fbee70339f7dcbc979f448800ecfff0f17
diff --git a/include/media/IOMX.h b/include/media/IOMX.h
index 1c39b9c..ffa6d6d 100644
--- a/include/media/IOMX.h
+++ b/include/media/IOMX.h
@@ -261,7 +261,7 @@
 
 protected:
     // check if the codec is secure.
-    virtual bool isSecure(IOMX::node_id node) {
+    virtual bool isSecure(IOMX::node_id /*node*/) {
         return false;
     }
 };