app: Optimize ipmi complete code

Encapsulate the custom status return code into an ipmi method and
then use it in cpp.

Change-Id: If1ce2bbb1a234c574bc89832dbb87004937d1d38
Signed-off-by: George Liu <liuxiwei@ieisystem.com>
diff --git a/app/channel.cpp b/app/channel.cpp
index efed5c1..ea737d5 100644
--- a/app/channel.cpp
+++ b/app/channel.cpp
@@ -17,6 +17,16 @@
 using namespace phosphor::logging;
 using namespace sdbusplus::error::xyz::openbmc_project::common;
 
+namespace ipmi
+{
+constexpr Cc ccPayloadTypeNotSupported = 0x80;
+
+static inline auto responsePayloadTypeNotSupported()
+{
+    return response(ccPayloadTypeNotSupported);
+}
+} // namespace ipmi
+
 namespace cipher
 {
 
@@ -131,8 +141,7 @@
     if (!ipmi::isValidPayloadType(static_cast<ipmi::PayloadType>(payloadType)))
     {
         lg2::debug("Get channel cipher suites - Invalid payload type");
-        constexpr uint8_t ccPayloadTypeNotSupported = 0x80;
-        return ipmi::response(ccPayloadTypeNotSupported);
+        return ipmi::responsePayloadTypeNotSupported();
     }
 
     if (!recordInit)