PLDM:Use new alias of DBUS_TIMEOUT for bus.call

This commit uses a new global variable for DBUS_TIMEOUT which is included as an input parameter for bus.call dbus calls. The new alias makes the bus.call function shorter and readable.

Change-Id: I336c97bc0631d5370ff3648e41f50e3e283d771b
Signed-off-by: vkaverap@in.ibm.com <vkaverap@in.ibm.com>
diff --git a/requester/mctp_endpoint_discovery.cpp b/requester/mctp_endpoint_discovery.cpp
index 5767314..bc50ee5 100644
--- a/requester/mctp_endpoint_discovery.cpp
+++ b/requester/mctp_endpoint_discovery.cpp
@@ -29,9 +29,7 @@
         auto method = bus.new_method_call(
             "xyz.openbmc_project.MCTP", "/xyz/openbmc_project/mctp",
             "org.freedesktop.DBus.ObjectManager", "GetManagedObjects");
-        auto reply = bus.call(
-            method,
-            std::chrono::duration_cast<microsec>(sec(DBUS_TIMEOUT)).count());
+        auto reply = bus.call(method, dbusTimeout);
         reply.read(objects);
     }
     catch (const std::exception& e)