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: I96286490697ce5d7fecc1c9c358f5f1d054137ec
diff --git a/flash.hpp b/flash.hpp
index c276017..0da94de 100644
--- a/flash.hpp
+++ b/flash.hpp
@@ -29,7 +29,7 @@
     /**
      * @brief Takes action when the state of the activation service file changes
      */
-    virtual void onStateChanges(sdbusplus::message::message& msg) = 0;
+    virtual void onStateChanges(sdbusplus::message_t& msg) = 0;
 };
 
 } // namespace updater