Discard the cached BLE packet

When using a BLE connection, it's not sufficient to purge the buffers of
the underlying I/O stream. The locally cached BLE packet needs to be
discarded also.

src/mares_iconhd.c

@@ -327,6 +327,8 @@ mares_iconhd_transfer (mares_iconhd_device_t *device, const unsigned char comman
 
 		// Discard any garbage bytes.
 		dc_iostream_purge (device->iostream, DC_DIRECTION_INPUT);
+		device->available = 0;
+		device->offset = 0;
 	}
 
 	return DC_STATUS_SUCCESS;