bus: fsl-mc: dpio: add frame descriptor and scatter/gather APIs

Add global definitions for DPAA2 frame descriptors and scatter
gather entries.

Signed-off-by: Roy Pledge <Roy.Pledge@nxp.com>
Signed-off-by: Stuart Yoder <stuart.yoder@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>