PEL: Trace when the send-to-host setting changes

Something in the journal will make it easier to remember this setting
may have been switched off when someone asks why PELs haven't been sent
to the host.  It will also provide a timestamp of when the setting was
changed if someone wanted to know.

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: I14170b2c8fc0b96b030f42f7408fdf995cd998b1
diff --git a/extensions/openpower-pels/data_interface.cpp b/extensions/openpower-pels/data_interface.cpp
index fecaa49..9f0a218 100644
--- a/extensions/openpower-pels/data_interface.cpp
+++ b/extensions/openpower-pels/data_interface.cpp
@@ -141,6 +141,13 @@
     _properties.emplace_back(std::make_unique<PropertyWatcher<DataInterface>>(
         bus, object_path::enableHostPELs, interface::enable, "Enabled", *this,
         [this](const auto& value) {
+            if (std::get<bool>(value) != this->_sendPELsToHost)
+            {
+                log<level::INFO>(
+                    fmt::format("The send PELs to host setting changed to {}",
+                                std::get<bool>(value))
+                        .c_str());
+            }
             this->_sendPELsToHost = std::get<bool>(value);
         }));