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: Ibc25db433a6926f7ee43ea83312c3ac14f480c33
diff --git a/extensions/openpower-pels/data_interface.hpp b/extensions/openpower-pels/data_interface.hpp
index c0e8c45..90f0aa2 100644
--- a/extensions/openpower-pels/data_interface.hpp
+++ b/extensions/openpower-pels/data_interface.hpp
@@ -573,7 +573,7 @@
      *
      * @param[in] bus - The sdbusplus bus object
      */
-    explicit DataInterface(sdbusplus::bus::bus& bus);
+    explicit DataInterface(sdbusplus::bus_t& bus);
 
     /**
      * @brief Finds the D-Bus service name that hosts the
@@ -814,7 +814,7 @@
      *        When the motherboard is found, it then adds a PropertyWatcher
      *        for the motherboard CCIN.
      */
-    void motherboardIfaceAdded(sdbusplus::message::message& msg);
+    void motherboardIfaceAdded(sdbusplus::message_t& msg);
 
     /**
      * @brief Adds the Ufcs- prefix to the location code passed in
@@ -839,7 +839,7 @@
     /**
      * @brief The sdbusplus bus object for making D-Bus calls.
      */
-    sdbusplus::bus::bus& _bus;
+    sdbusplus::bus_t& _bus;
 
     /**
      * @brief The interfacesAdded match object used to wait for inventory