clean up more pedantic compile warnings

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I84790e29a24c73a65c9770c6836b482386cc0ab7
diff --git a/sdbusplus/timer.hpp b/sdbusplus/timer.hpp
index d94cebb..69cbcb2 100644
--- a/sdbusplus/timer.hpp
+++ b/sdbusplus/timer.hpp
@@ -178,7 +178,8 @@
             CLOCK_MONOTONIC, // Time base
             UINT64_MAX,      // Expire time - way long time
             0,               // Use default event accuracy
-            [](sd_event_source* eventSource, uint64_t usec, void* userData) {
+            [](sd_event_source* /*eventSource*/, uint64_t /*usec*/,
+               void* userData) {
                 auto timer = static_cast<Timer*>(userData);
                 return timer->timeoutHandler();
             },     // Callback handler on timeout