This way we have one central definition of it, and user can select it as
needed.  Note that we now also always select it when CONFIG_DMA_API_DEBUG
is select, which fixes some incorrect checks in a few network drivers.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NAnshuman Khandual <khandual@linux.vnet.ibm.com>