picoxcell: support for Picochip picoxcell devices

picoXcell is a family of femtocell devices with an ARM application
processor and picoArray DSP processor array.

This patch adds support for picoXcell boards to be booted using the
device tree registering the VIC's, UART's and timers.

v3:	- fixup vic compatible string in binding
v2:	- cleanup empty mach headers
	- convert to of_platform_populate()
	- simplify uncompress.h
	- split vic node into 2 devices
	- add missing __initconst attributes

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