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: I86dfa77a53a306b0e868eeb82de30b270704c455
diff --git a/mainloop.cpp b/mainloop.cpp
index 6ab8e9c..85770a2 100644
--- a/mainloop.cpp
+++ b/mainloop.cpp
@@ -303,7 +303,7 @@
                           std::move(info));
 }
 
-MainLoop::MainLoop(sdbusplus::bus::bus&& bus, const std::string& param,
+MainLoop::MainLoop(sdbusplus::bus_t&& bus, const std::string& param,
                    const std::string& path, const std::string& devPath,
                    const char* prefix, const char* root,
                    const std::string& instanceId,