staging: fsl-mc: bus: add DPCON object APIs

This patch adds the command building/parsing wrapper functions
for the DPCON object. The binary interface version is v3.2.

A DPCON (DataPath Concentrator) is an aggregator object that
allows ingress frames from multiple hardware queues to be seen
as coming from a single source, from the CPU point of view.

Signed-off-by: Ioana Radulescu <ruxandra.radulescu@nxp.com>
Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: Stuart Yoder <stuart.yoder@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>