In some cases client code may need the dma-driver to skip the unmap of source
and/or destination buffers.  Setting these flags indicates to the driver to
skip the unmap step.  In this regard async_xor is currently broken in that it
allows the destination buffer to be unmapped while an operation is still in
progress, i.e. when the number of sources exceeds the hardware channel's
maximum (fixed in a subsequent patch).
Acked-by: NSaeed Bishara <saeed@marvell.com>
Acked-by: NMaciej Sosnowski <maciej.sosnowski@intel.com>
Acked-by: NHaavard Skinnemoen <haavard.skinnemoen@atmel.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>