Print the failing filename in the journal msg

Instead of hiding the name of the file that had the failed access in the
journal metadata, put it in the journal message so debug is easier.

Uses the fmt library.

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: Ice3958ffb576adf0b06ef7eab7d2fc03aa526819
diff --git a/fan_speed.cpp b/fan_speed.cpp
index 65e5655..e990410 100644
--- a/fan_speed.cpp
+++ b/fan_speed.cpp
@@ -6,6 +6,8 @@
 #include "sensorset.hpp"
 #include "sysfs.hpp"
 
+#include <fmt/format.h>
+
 #include <phosphor-logging/elog-errors.hpp>
 #include <xyz/openbmc_project/Control/Device/error.hpp>
 
@@ -39,8 +41,8 @@
             auto file = sysfs::make_sysfs_path(_ioAccess->path(), _type, _id,
                                                entry::target);
 
-            log<level::INFO>("Logging failing sysfs file",
-                             phosphor::logging::entry("FILE=%s", file.c_str()));
+            log<level::INFO>(
+                fmt::format("Failing sysfs file: {}", file).c_str());
 
             exit(EXIT_FAILURE);
         }
@@ -75,8 +77,7 @@
                                                    _id, entry::enable);
 
             log<level::INFO>(
-                "Logging failing sysfs file",
-                phosphor::logging::entry("FILE=%s", fullPath.c_str()));
+                fmt::format("Failing sysfs file: {}", fullPath).c_str());
 
             exit(EXIT_FAILURE);
         }