use sdbusplus unpack syntax

Rather than defining a variable and then reading it from a message,
sdbusplus also supports directly unpack-ing from the message.  Use
this syntax instead as it is more efficient and succinct.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I0d9f919d527eeaa320c69fecc5661a380cbca4d6
diff --git a/dump-extensions/openpower-dumps/op_dump_util.cpp b/dump-extensions/openpower-dumps/op_dump_util.cpp
index fe3f236..7846c48 100644
--- a/dump-extensions/openpower-dumps/op_dump_util.cpp
+++ b/dump-extensions/openpower-dumps/op_dump_util.cpp
@@ -41,8 +41,8 @@
             bus.new_method_call(service.c_str(), policy, property, "Get");
         method.append(enable, "Enabled");
         auto reply = bus.call(method);
-        std::variant<bool> v;
-        reply.read(v);
+        auto v = reply.unpack<std::variant<bool>>();
+
         isEnabled = std::get<bool>(v);
     }
     catch (const sdbusplus::exception::SdBusError& e)