Provide a fmtlib ostream formatter for SysPwrMode enum

fmtlib removed support for automatically formatting enums as integers
in version 9. See fmtlib/fmt#1841.

Signed-off-by: Eddie James <[email protected]>
Change-Id: I6a5d04187e55c94d39d8b5ee334f9a37c93081ce

Author: Eddie James

occ_command.hpp

@@ -3,6 +3,8 @@
 #include "occ_errors.hpp"
 #include "utils.hpp"
 
+#include <fmt/ostream.h>
+
 #include <org/open_power/OCC/PassThrough/server.hpp>
 #include <sdbusplus/bus.hpp>
 #include <sdbusplus/server/object.hpp>
@@ -171,3 +173,7 @@ class OccCommand
 
 } // namespace occ
 } // namespace open_power
+
+template <>
+struct fmt::formatter<open_power::occ::SysPwrMode> : ostream_formatter
+{};