[ncp] simplify unimplemented commands (#4490)

src/ncp/ncp_base.cpp

@@ -884,16 +884,13 @@ otError NcpBase::HandleCommand(uint8_t aHeader)
 
 #if OPENTHREAD_MTD || OPENTHREAD_FTD
     case SPINEL_CMD_NET_SAVE:
-        error = CommandHandler_NET_SAVE(aHeader);
+    case SPINEL_CMD_NET_RECALL:
+        error = OT_ERROR_NOT_IMPLEMENTED;
         break;
 
     case SPINEL_CMD_NET_CLEAR:
         error = CommandHandler_NET_CLEAR(aHeader);
         break;
-
-    case SPINEL_CMD_NET_RECALL:
-        error = CommandHandler_NET_RECALL(aHeader);
-        break;
 #endif // OPENTHREAD_MTD || OPENTHREAD_FTD
 
     default:

src/ncp/ncp_base.hpp

@@ -365,9 +365,7 @@ protected:
     otError CommandHandler_POKE(uint8_t aHeader);
 #endif
 #if OPENTHREAD_MTD || OPENTHREAD_FTD
-    otError CommandHandler_NET_SAVE(uint8_t aHeader);
     otError CommandHandler_NET_CLEAR(uint8_t aHeader);
-    otError CommandHandler_NET_RECALL(uint8_t aHeader);
 #endif
 
     // ----------------------------------------------------------------------------

src/ncp/ncp_base_mtd.cpp

@@ -120,14 +120,13 @@ static uint8_t ExternalRoutePreferenceToFlagByte(int aPreference)
         flags = SPINEL_ROUTE_PREFERENCE_LOW;
         break;
 
-    case OT_ROUTE_PREFERENCE_MED:
-        flags = SPINEL_ROUTE_PREFERENCE_MEDIUM;
-        break;
-
     case OT_ROUTE_PREFERENCE_HIGH:
         flags = SPINEL_ROUTE_PREFERENCE_HIGH;
         break;
 
+    case OT_ROUTE_PREFERENCE_MED:
+        // fall through
+
     default:
         flags = SPINEL_ROUTE_PREFERENCE_MEDIUM;
         break;
@@ -242,21 +241,11 @@ exit:
     return error;
 }
 
-otError NcpBase::CommandHandler_NET_SAVE(uint8_t aHeader)
-{
-    return PrepareLastStatusResponse(aHeader, SPINEL_STATUS_UNIMPLEMENTED);
-}
-
 otError NcpBase::CommandHandler_NET_CLEAR(uint8_t aHeader)
 {
     return PrepareLastStatusResponse(aHeader, ThreadErrorToSpinelStatus(otInstanceErasePersistentInfo(mInstance)));
 }
 
-otError NcpBase::CommandHandler_NET_RECALL(uint8_t aHeader)
-{
-    return PrepareLastStatusResponse(aHeader, SPINEL_STATUS_UNIMPLEMENTED);
-}
-
 template <> otError NcpBase::HandlePropertyGet<SPINEL_PROP_NET_SAVED>(void)
 {
     return mEncoder.WriteBool(otDatasetIsCommissioned(mInstance));