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: I44db990b2509a639c17765e7db10314ed858bd4d
diff --git a/physical.hpp b/physical.hpp
index 7a3c912..3592494 100644
--- a/physical.hpp
+++ b/physical.hpp
@@ -45,8 +45,8 @@
      * @param[in] ledPath   - sysfs path where this LED is exported
      * @param[in] color     - led color name
      */
-    Physical(sdbusplus::bus::bus& bus, const std::string& objPath,
-             SysfsLed& led, const std::string& color = "") :
+    Physical(sdbusplus::bus_t& bus, const std::string& objPath, SysfsLed& led,
+             const std::string& color = "") :
         PhysicalIfaces(bus, objPath.c_str(),
                        PhysicalIfaces::action::defer_emit),
         led(led)