Remove size_t from SetPropertyReturnValue

This enum is only ever used as an enum.  Let the compiler decide what
underlying type to use.

Change-Id: Ieda7835ab346c46d8a1153a8e8eb65e45ae1648c
Signed-off-by: Ed Tanous <edtanous@google.com>
diff --git a/include/sdbusplus/asio/object_server.hpp b/include/sdbusplus/asio/object_server.hpp
index 283b52e..2840373 100644
--- a/include/sdbusplus/asio/object_server.hpp
+++ b/include/sdbusplus/asio/object_server.hpp
@@ -33,7 +33,7 @@
     virtual int call(message_t& m) = 0;
 };
 
-enum class SetPropertyReturnValue : size_t
+enum class SetPropertyReturnValue
 {
     fail = 0,
     valueUpdated,