staging: fsl-dpaa2/ethsw: Add APIs for DPSW object

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

Signed-off-by: Razvan Stefanescu <razvan.stefanescu@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>