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: I17807e986cefa6a3d9e757c533ac373035438aed
diff --git a/include/dbus/file_notifier.hpp b/include/dbus/file_notifier.hpp
index 16b61b8..c887ab2 100644
--- a/include/dbus/file_notifier.hpp
+++ b/include/dbus/file_notifier.hpp
@@ -26,7 +26,7 @@
      * @param filePath - full path of the CPER log JSON file.
      * @param entry - index of the DBus file path object.
      */
-    CperFileNotifier(sdbusplus::bus::bus& bus, const std::string& filePath,
+    CperFileNotifier(sdbusplus::bus_t& bus, const std::string& filePath,
                      uint64_t entry) :
         FileNotifierInterface(bus, generatePath(entry).c_str(),
                               action::emit_no_signals),
@@ -46,7 +46,7 @@
      */
     uint64_t entry;
 
-    sdbusplus::bus::bus& bus;
+    sdbusplus::bus_t& bus;
 
     /**
      * @brief Generate a path for the CperFileNotifier DBus object.