powerpc/85xx: Update device tree handling for SRIO

Update device tree handling for SRIO controller to support updated
fsl,srio device tree binding.

We handle disabling of individual ports, the whole controller, RMU, and
RMAN.  Additionally, we setup the SRIO related LIODNs in the device
tree.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>