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: I9029cc722e7712633c15436bd3868d8c3209f567
diff --git a/control/json/event.hpp b/control/json/event.hpp
index 0873c06..e0bdd06 100644
--- a/control/json/event.hpp
+++ b/control/json/event.hpp
@@ -150,7 +150,7 @@
 
   private:
     /* The sdbusplus bus object */
-    sdbusplus::bus::bus& _bus;
+    sdbusplus::bus_t& _bus;
 
     /* The event's manager */
     Manager* _manager;