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/fan_speed.hpp b/fan_speed.hpp
index f1a3fdb..fd943e1 100644
--- a/fan_speed.hpp
+++ b/fan_speed.hpp
@@ -31,7 +31,7 @@
      */
     FanSpeed(std::unique_ptr<hwmonio::HwmonIOInterface> io,
              const std::string& devPath, const std::string& id,
-             sdbusplus::bus::bus& bus, const char* objPath, bool defer,
+             sdbusplus::bus_t& bus, const char* objPath, bool defer,
              uint64_t target) :
         FanSpeedObject(bus, objPath,
                        defer ? FanSpeedObject::action::emit_no_signals