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/entry_points.cpp b/extensions/openpower-pels/entry_points.cpp
index c904afb..d9e44c7 100644
--- a/extensions/openpower-pels/entry_points.cpp
+++ b/extensions/openpower-pels/entry_points.cpp
@@ -21,10 +21,10 @@
 #include "manager.hpp"
 #include "pldm_interface.hpp"
 
-#include <fmt/format.h>
-
 #include <phosphor-logging/log.hpp>
 
+#include <format>
+
 namespace openpower
 {
 namespace pels
@@ -69,7 +69,7 @@
         // Log message and continue,
         // This is to help continue creating PEL in raw format.
         log<level::ERR>(
-            fmt::format("Failed to set PDBG_DTB: ({})", strerror(errno))
+            std::format("Failed to set PDBG_DTB: ({})", strerror(errno))
                 .c_str());
     }
 #endif