PEL: Add getPELJSON D-Bus method stub

In the future this will return the full PEL in JSON.  This stub is going
in so the phosphor-dbus-interface yaml for the method can merge without
breaking the build complaining about an unimplemented pure virtual.

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: I4a0b98a263b544fffba2cc832b4817e7d2ad155b
diff --git a/extensions/openpower-pels/manager.cpp b/extensions/openpower-pels/manager.cpp
index e64e858..7e42020 100644
--- a/extensions/openpower-pels/manager.cpp
+++ b/extensions/openpower-pels/manager.cpp
@@ -641,6 +641,11 @@
     return {_logManager.lastEntryID(), _repo.lastPelID()};
 }
 
+std::string Manager::getPELJSON(uint32_t /*obmcLogID*/)
+{
+    return std::string{};
+}
+
 void Manager::checkPelAndQuiesce(std::unique_ptr<openpower::pels::PEL>& pel)
 {
     if ((pel->userHeader().severity() ==