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: I96286490697ce5d7fecc1c9c358f5f1d054137ec
diff --git a/static/flash.cpp b/static/flash.cpp
index 748a6cf..cdf0683 100644
--- a/static/flash.cpp
+++ b/static/flash.cpp
@@ -57,8 +57,7 @@
     }
 }
 
-void Activation::onStateChanges(
-    [[maybe_unused]] sdbusplus::message::message& msg)
+void Activation::onStateChanges([[maybe_unused]] sdbusplus::message_t& msg)
 {
 #ifdef BMC_STATIC_DUAL_IMAGE
     uint32_t newStateID;