staging: fsl-dpaa2/eth: Add APIs for DPNI objects

Add the command build/parse APIs for operating on DPNI objects through
the DPAA2 Management Complex.

Signed-off-by: Ioana Radulescu <ruxandra.radulescu@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>