Signal NVM data change in LoRaMacMc* functions (#1340)

The various multicast management functions provided by the library
modify data stored in NVM and thus need to signal to the NVM layer when
the data changes.

Author: janakj

src/mac/LoRaMac.c

@@ -4917,6 +4917,7 @@ LoRaMacStatus_t LoRaMacMcChannelSetup( McChannelParams_t *channel )
     }
 
     Nvm.MacGroup2.MulticastChannelList[channel->GroupID].ChannelParams = *channel;
+    MacCtx.MacFlags.Bits.NvmHandle = 1;
 
     if( channel->IsRemotelySetup == true )
     {
@@ -4969,6 +4970,7 @@ LoRaMacStatus_t LoRaMacMcChannelDelete( AddressIdentifier_t groupID )
     memset1( ( uint8_t* )&channel, 0, sizeof( McChannelParams_t ) );
 
     Nvm.MacGroup2.MulticastChannelList[groupID].ChannelParams = channel;
+    MacCtx.MacFlags.Bits.NvmHandle = 1;
     return LORAMAC_STATUS_OK;
 }
 
@@ -5040,6 +5042,7 @@ LoRaMacStatus_t LoRaMacMcChannelSetupRxParams( AddressIdentifier_t groupID, McRx
     {
         // Apply parameters
         Nvm.MacGroup2.MulticastChannelList[groupID].ChannelParams.RxParams = *rxParams;
+        MacCtx.MacFlags.Bits.NvmHandle = 1;
     }
     else
     {