PEL: switch fmt::format to use std::format

fmt::format is supported in the c++ std. This will
    help to remove fmt package dependency.

Change-Id: I89f0a5b67bbfe54168a20e93c989a1ae87f54503
Signed-off-by: Jayanth Othayoth <ojayanth@in.ibm.com>
diff --git a/extensions/openpower-pels/journal.cpp b/extensions/openpower-pels/journal.cpp
index 18359fd..70a4552 100644
--- a/extensions/openpower-pels/journal.cpp
+++ b/extensions/openpower-pels/journal.cpp
@@ -17,10 +17,10 @@
 
 #include "util.hpp"
 
-#include <fmt/format.h>
-
 #include <phosphor-logging/log.hpp>
 
+#include <format>
+
 namespace openpower::pels
 {
 
@@ -64,7 +64,7 @@
     if (duration.count() > 100)
     {
         log<level::INFO>(
-            fmt::format("Journal sync took {}ms", duration.count()).c_str());
+            std::format("Journal sync took {}ms", duration.count()).c_str());
     }
 }