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: Ief05bd757cffb1453e058a719ee4b060861752e7
diff --git a/cold-redundancy/util.cpp b/cold-redundancy/util.cpp
index fea972e..8946d30 100644
--- a/cold-redundancy/util.cpp
+++ b/cold-redundancy/util.cpp
@@ -35,7 +35,7 @@
     phosphor::power::util::getProperty<bool>(
         "xyz.openbmc_project.State.Decorator.OperationalStatus", "functional",
         pathStr, "xyz.openbmc_project.PSUSensor",
-        static_cast<sdbusplus::bus::bus&>(*conn), result);
+        static_cast<sdbusplus::bus_t&>(*conn), result);
 
     if (!result)
     {