prefer std::format over fmt

Since C++20, std::format has existed so prefer that.  For the single
fmt::print call we can use stdplus::print until GCC supports the std
one.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I4c8af58966fb7330dee20fb13ae2ef11d8a823c7
diff --git a/fan_speed.cpp b/fan_speed.cpp
index 9ce625b..067e882 100644
--- a/fan_speed.cpp
+++ b/fan_speed.cpp
@@ -6,11 +6,11 @@
 #include "sensorset.hpp"
 #include "sysfs.hpp"
 
-#include <fmt/format.h>
-
 #include <phosphor-logging/elog-errors.hpp>
 #include <xyz/openbmc_project/Control/Device/error.hpp>
 
+#include <format>
+
 using namespace phosphor::logging;
 
 namespace hwmon
@@ -41,7 +41,7 @@
             auto file = sysfs::make_sysfs_path(_ioAccess->path(), _type, _id,
                                                entry::target);
 
-            log<level::INFO>(fmt::format("Failing sysfs file: {} errno: {}",
+            log<level::INFO>(std::format("Failing sysfs file: {} errno: {}",
                                          file, e.code().value())
                                  .c_str());
 
@@ -77,7 +77,7 @@
             auto fullPath = sysfs::make_sysfs_path(_ioAccess->path(), type::pwm,
                                                    _id, entry::enable);
 
-            log<level::INFO>(fmt::format("Failing sysfs file: {} errno: {}",
+            log<level::INFO>(std::format("Failing sysfs file: {} errno: {}",
                                          fullPath, e.code().value())
                                  .c_str());