sdbusplus::asio: Use the default bus

The documentation says that the default bus calls are the ones to use
instead of the open bus calls to reduce resources.

Change-Id: I719494adf2e97e94bb5a9925064cda6cfdd28047
Signed-off-by: Vernon Mauery <vernon.mauery@linux.intel.com>
diff --git a/sdbusplus/asio/connection.hpp b/sdbusplus/asio/connection.hpp
index ec54ae4..8fbd08a 100644
--- a/sdbusplus/asio/connection.hpp
+++ b/sdbusplus/asio/connection.hpp
@@ -47,7 +47,7 @@
   public:
     // default to system bus
     connection(boost::asio::io_service& io) :
-        sdbusplus::bus::bus(sdbusplus::bus::new_system()), io_(io), socket(io_)
+        sdbusplus::bus::bus(sdbusplus::bus::new_default()), io_(io), socket(io_)
     {
         socket.assign(get_fd());
         read_wait();