docs: ABI: sysfs-driver-dma-ioatdma: what starts with /sys

This is the only file where the /sys doesn't start with
a /.

So, rename them to:

sys -> /sys

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/f4c53fff9696a61ff0e144fee237a9527982626d.1604312590.git.mchehab+huawei@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

dmaengine: ioatdma: Add ABI document

ABI document added to describe all sysfs variables
for dma

Signed-off-by: Ujjal Singh <ujjal.singh@intel.com>
Acked-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>