PEL: Add getLocationCode call to inv callout

Instead of getting the location code, PN, SN, and CCIN all in one
function call, split getting the location code into its own function.
This way, if there is a location code but not the VPD fields, we can
still have the location code in the callout.

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: I02f1b18319c34fffce79ad31da74e2114ceb5c95
diff --git a/test/openpower-pels/mocks.hpp b/test/openpower-pels/mocks.hpp
index c003dd8..1fd679f 100644
--- a/test/openpower-pels/mocks.hpp
+++ b/test/openpower-pels/mocks.hpp
@@ -30,10 +30,11 @@
     MOCK_METHOD(std::string, getHostState, (), (const override));
     MOCK_METHOD(std::string, getMotherboardCCIN, (), (const override));
     MOCK_METHOD(void, getHWCalloutFields,
-                (const std::string&, std::string&, std::string&, std::string&,
-                 std::string&),
+                (const std::string&, std::string&, std::string&, std::string&),
                 (const override));
     MOCK_METHOD(std::string, getSystemType, (), (const override));
+    MOCK_METHOD(std::string, getLocationCode, (const std::string&),
+                (const override));
 
     void changeHostState(bool newState)
     {