Add more informations in OnNvmDataChange

[adixmasz]

FEATURE REQUEST

I would like to ask for a small improvement in OnNvmDataChange callback.
Currently I use LoraMac-node 4.6.0.

This callback has no information about what part of LoRaMacNvmData_t was updated.
I propose to add enum type, for example:

typedef enum
{
    LORAMAC_HANDLER_NVM_CRYPTO = (1<<0),
    LORAMAC_HANDLER_NVM_MACGROUP1 = (1<<1),
    LORAMAC_HANDLER_NVM_MACGROUP2 = (1<<2),
    LORAMAC_HANDLER_NVMSECUREELEMENT = (1<<3),
    LORAMAC_HANDLER_NVM_REGIONGROUP1 = (1<<4),
    LORAMAC_HANDLER_NVM_REGIONGROUP2 = (1<<5),
    LORAMAC_HANDLER_NVM_CLASSB = (1<<6),
}LmHandlerNvmContextFlags_t;

This enum type can be use in:

void LmHandlerProcess( void )
{
    uint16_t size = 0;

    // Process Radio IRQ
    if( Radio.IrqProcess != NULL )
    {
        Radio.IrqProcess( );
    }

    // Processes the LoRaMac events
    LoRaMacProcess( );

    // Store to NVM if required

   int operationFlags = 0;      // THIS WAS ADDED
    size = NvmDataMgmtStore(&operationFlags );

And pass here to callback:

    if( size > 0 )
    {
        if( LmHandlerCallbacks->OnNvmDataChange != NULL )
        {
            LmHandlerCallbacks->OnNvmDataChange( LORAMAC_HANDLER_NVM_STORE, size,, operationFlags );
        }
    }

With this modification user can analyze what NVM do:

void OnNvmDataChange( LmHandlerNvmContextStates_t state, uint16_t size, int flag )
{
    if(flag & LORAMAC_HANDLER_NVM_MACGROUP1 )
    {
        printf("MacGroup1 was updated");
    }
    // etc
}

I kindly request for that feature, in my opinion it can be helpfull for example during NVM debuging and checking if my application do not crash internal flash memory to fast.