all: Use stdplus::print over std::fprintf

Replacing `std::fprintf` with `stdplus::print`.
No logical change.

Tested: Buildable.
Signed-off-by: Michael Shen <gpgpgp@google.com>
Change-Id: I7050885c13e33244a4128aa519d163fd5b725098
diff --git a/util.cpp b/util.cpp
index 95e4d12..27b6b79 100644
--- a/util.cpp
+++ b/util.cpp
@@ -16,6 +16,7 @@
 
 #include <nlohmann/json.hpp>
 #include <phosphor-logging/elog-errors.hpp>
+#include <stdplus/print.hpp>
 #include <xyz/openbmc_project/Common/error.hpp>
 
 #include <cstdint>
@@ -81,7 +82,7 @@
         }
         else
         {
-            std::fprintf(stderr, "Unable to read file %s.\n", fileName.c_str());
+            stdplus::print(stderr, "Unable to read file {}.\n", fileName);
         }
     }