rpc_client: fix ACK counter start value

Start the ACK counter at 0, not negative. This prevents the possibility
of too many buffers pending on the receiving device, which would cause
buffers to drop and hence the upload to fail. This slightly reduces
write throughput.

Signed-off-by: Jordan Yates <jordan@embeint.com>

Author: JordanYates

src/infuse_iot/rpc_client.py

@@ -127,7 +127,7 @@ def _run_data_send_core(
             return self._finalise_command(recv, rsp_decoder)
 
         # Send data payloads chunked as requested
-        ack_cnt = -ack_period
+        ack_cnt = 0
         offset = 0
         for chunk_id, chunk in enumerate(data):
             hdr = rpc.DataHeader(self._request_id, chunk_id if packet_idx else offset)