picoxcell: add the DTS for pc3x2 and pc3x3 devices

This describes the basic hierarchy of picoxcell pc3x3 devices including
clocks and bus interconnect.  Some onchip devices are currently omitted
as there haven't been bindings created for them.

v2:	- change timer compatible strings to be more soc specific
	- split vic node into 2 devices

Signed-off-by: Jamie Iles <jamie@jamieiles.com>