sdbusplus: use shorter type aliases

The sdbusplus headers provide shortened aliases for many types.
Switch to using them to provide better code clarity and shorter
lines.  Possible replacements are for:
  * bus_t
  * exception_t
  * manager_t
  * match_t
  * message_t
  * object_t
  * slot_t

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I29672cb229bd07022b00f52105ac1d50ecacca62
diff --git a/util.hpp b/util.hpp
index 442bd22..e68c9c0 100644
--- a/util.hpp
+++ b/util.hpp
@@ -17,7 +17,7 @@
  *
  * @return service name on success and exception on failure
  */
-std::string getService(sdbusplus::bus::bus& bus, const std::string& objectPath,
+std::string getService(sdbusplus::bus_t& bus, const std::string& objectPath,
                        const std::string& interface);
 
 /**