raw/ioat: add skeleton for VFIO/UIO based DSA device

raw/ioat: add skeleton for VFIO/UIO based DSA device

Add in the basic probe/remove skeleton code for DSA devices which are bound
directly to vfio or uio driver. The kernel module for supporting these uses
the "idxd" name, so that name is used as function and file prefix to avoid
conflict with existing "ioat" prefixed functions.

Since we are adding new files to the driver and there will be common
definitions shared between the various files, we create a new internal
header file ioat_private.h to hold common macros and function prototypes.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Reviewed-by: Kevin Laatz <kevin.laatz@intel.com>
Acked-by: Radu Nicolau <radu.nicolau@intel.com>