cmn600: Add the ccix programming for cmn600

The patch introduces the ccix programming so that
host could communicate with the CCIX complaint endpoint.
Currently it is being verified with the Xilinx Alveo-U280
production card

Change-Id: I07ed1f7eb1c8ae6eb58b1c168b9ee144c1a7020a
Signed-off-by: Deepak Pandey <Deepak.Pandey@arm.com>