aom_integer_test: Use correct var in decode fail test.

Use bytes_written in aom_uleb_decode() call when operating on
locally encoded LEB128 data.

Change-Id: I969b4ffe42897b2a5d4611a2217a8be560dd5e86
diff --git a/test/aom_integer_test.cc b/test/aom_integer_test.cc
index 83e989d..948778b 100644
--- a/test/aom_integer_test.cc
+++ b/test/aom_integer_test.cc
@@ -146,8 +146,8 @@
                             &encode_buffer[0], &bytes_written),
             0);
   size_t value_size = 0;
-  ASSERT_EQ(aom_uleb_decode(&encode_buffer[0], kMaximumLeb128CodedSize,
-                            &decoded_value, &value_size),
+  ASSERT_EQ(aom_uleb_decode(&encode_buffer[0], bytes_written, &decoded_value,
+                            &value_size),
             -1);
 }