dma_sniffer_set_byte_swap_enabled() function

Enable the Sniffer byte swap function Locally perform a byte reverse on the sniffed data, before feeding into checksum. Note that the sniff hardware is downstream of the DMA channel byteswap performed in the read master: if channel_config_set_bswap() and dma_sniffer_set_byte_swap_enabled() are both enabled, their effects cancel from the sniffer’s point of view.