gdma_buffer_mount_flags struct

Whether to mark the list item as the "EOF" item. Note, an "EOF" descriptor can be interrupted differently by peripheral. But it doesn't mean to terminate a DMA link (use `mark_final` instead). EOF link list item can also trigger an interrupt.

Whether to terminate the DMA link list at this item. Note, DMA engine will stop at this item and trigger an interrupt. If `mark_final` is not set, this list item will point to the next item, and wrap around to the head item if it's the last one in the list.