core-mqtt-mock: Fix logging stack mocks

The LogWarning macro was being defined via SdkLogError instead of
SdkLogWarning, which made some unit test cases inaccurate.
LogWarning is now defined using the SdkLogWarning fake function.

Signed-off-by: Reuben Cartwright <[email protected]>

applications/helpers/logging/mocks/inc/logging_stack.h

@@ -35,7 +35,7 @@ DECLARE_FAKE_VOID_FUNC_VARARG( SdkLogError,
 DECLARE_FAKE_VOID_FUNC_VARARG( SdkLogWarn,
                                const char *,
                                ... );
-#define LogWarn( message )    ( SdkLogError message )
+#define LogWarn( message )    ( SdkLogWarn message )
 DECLARE_FAKE_VOID_FUNC_VARARG( SdkLogInfo,
                                const char *,
                                ... );