Initialize an uninitialized enum.

frameworks/av/media/codec2/tests/C2UtilTest.cpp:82:39: error: variable 'e3' is uninitialized when passed as a const reference argument here [-Werror,-Wuninitialized-const-reference]
    C2FieldDescriptor::namedValuesFor(e3);
                                      ^~

Bug: http://b/155835175
Test: mma in frameworks/av/media/codec2/tests
Change-Id: Iba83877b6dbe17a922ad71988f13a853050ae7c8
diff --git a/media/codec2/tests/C2UtilTest.cpp b/media/codec2/tests/C2UtilTest.cpp
index 59cd313..2d66df1 100644
--- a/media/codec2/tests/C2UtilTest.cpp
+++ b/media/codec2/tests/C2UtilTest.cpp
@@ -78,7 +78,7 @@
       { "value2", Enum3Value2 },
       { "value4", Enum3Value4 },
       { "invalid", Invalid } });
-    Enum3 e3;
+    Enum3 e3(Invalid);
     C2FieldDescriptor::namedValuesFor(e3);
 
     // upper case