Use input argument instead of macro in mqttDownloader_processReceivedDataBlock

[priyamourya25]

The param description for the API shows that dataLength is an input argument dataLength Decoded data block length.

This line should be
( void ) memset( data, ( int32_t ) '\0', mqttFileDownloader_CONFIG_BLOCK_SIZE );
changed to :
( void ) memset( data, ( int32_t ) '\0', *dataLength );

This is to avoid using constants if arguments are available for the same. The API does provide an interface to pass the dataLength and it should be used for manipulating the data buffer.

[priyamourya25]

Another instance of MACRO seen here:

aws-iot-core-mqtt-file-streams-embedded-c/source/MQTTFileDownloader.c

Line 357 in 690fb2b

size_t payloadSize = mqttFileDownloader_CONFIG_BLOCK_SIZE;

Better to use
size_t payloadSize = *decodedDataLength;