PEL: Support UserData padding in the testcases

Some testcase updates were missed when the fix was made to pad the
UserData section to 4 byte boundaries as required by the spec.

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: I8129a70cfd740155ca05089563dfc5d7e63bdc81
diff --git a/test/openpower-pels/pel_test.cpp b/test/openpower-pels/pel_test.cpp
index 9976c5c..afab5ca 100644
--- a/test/openpower-pels/pel_test.cpp
+++ b/test/openpower-pels/pel_test.cpp
@@ -265,9 +265,16 @@
     const auto& d = ud->data();
 
     std::string jsonString{d.begin(), d.end()};
-    std::string expected =
+
+    std::string expectedJSON =
         R"({"KEY1":"VALUE1","KEY2":"VALUE2","KEY3":"VALUE3"})";
-    EXPECT_EQ(jsonString, expected);
+
+    // The actual data is null padded to a 4B boundary.
+    std::vector<uint8_t> expectedData;
+    expectedData.resize(52, '\0');
+    memcpy(expectedData.data(), expectedJSON.data(), expectedJSON.size());
+
+    EXPECT_EQ(d, expectedData);
 
     // Ensure we can read this as JSON
     auto newJSON = nlohmann::json::parse(jsonString);