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: I768b8efcac262ef07cf75f06486c6144c090e91a
diff --git a/dbus.cpp b/dbus.cpp
index aee1654..49e0e03 100644
--- a/dbus.cpp
+++ b/dbus.cpp
@@ -29,7 +29,7 @@
 
 using namespace phosphor::logging;
 
-ObjectValueTree getManagedObjects(sdbusplus::bus::bus& bus,
+ObjectValueTree getManagedObjects(sdbusplus::bus_t& bus,
                                   const std::string& service,
                                   const std::string& objPath)
 {
@@ -46,7 +46,7 @@
     return interfaces;
 }
 
-DbusPropertyMap getAllProperties(sdbusplus::bus::bus& bus,
+DbusPropertyMap getAllProperties(sdbusplus::bus_t& bus,
                                  const std::string& service,
                                  const std::string& objPath,
                                  const std::string& interface)
@@ -63,7 +63,7 @@
     return properties;
 }
 
-DbusSubtree getSubtree(sdbusplus::bus::bus& bus, const std::string& root,
+DbusSubtree getSubtree(sdbusplus::bus_t& bus, const std::string& root,
                        int depth, const std::string& interface)
 {
     DbusSubtree tree;