libplatsupport: typedef gpio_level enum

This is required for allowing this data type to be used in CAmkES IDL4
definitions.

trivial: Style changed files

libplatsupport: typedef GPIO and MUX enums

The enums are typedef'd to allow the IDL4 files to be able to recognise
and use these special data types.

trivial: Style changed files

trivial: Update license

platsupport: Cleanup and add docs to GPIO iface

Parts of the header are cleaned up to remove duplicated checks in the
beginning of the functions. Also add documentation to the GPIO
interface.

platsupport: Change pending_status 'clear' type

A bool for suggesting to clear the interrupt flag represents the type
better than an int.

platsupport: Replace read/write w/ set/read_level

This is the second part of the change to remove the ability the chain
together pins in the driver level. Now that it's not possible to chain
together pins, we replace the read/write functions with pin unit level
functions.

platsupport: Remove GPIO set_next and next field

The functionality to be able to chain together GPIO pins is outside the
scope of the driver, this functionality should instead belong to a
utility library. This commit removes this from the drivers so that it
can be refactored into a library.

platsupport: Don't require plat/gpio.h on all plat

The Arm interface for gpio_sys_t doesn't require any platform
definitions and so we don't need to include a platform header file.

platsupport: GPIO API: Document the gpio_read/write

platsupport: GPIO API: Fix stack variable initialization bug

platsupport: GPIO API: Add new feature support and enhance documentation

* Add support for a default output state for GPIO output pins
^ Choose between GPIO_DIR_OUT_DEFAULT_[LOW|HIGH].
* Add set_next() for setting linked pins and supporting chaining.
* Add top-level API wrappers for gpio_read/write().

platsupport: GPIO API: Cleanup: Replace asserts and libc errnos with ZF_LOGF

platsupport: GPIO: Add IRQ enable/disable to GPIO API

This patch augments the platsupport GPIO API to enable the user of a GPIO pin
to enable and disable the IRQ signal for the pin.

platsupport: Mux API: Add a dependencies parameter to mux_sys_init

This is a workaround for the fact that we have no real dependency tree at the
moment. The two approaches to this problem were either:
* Add a gpio_sys_t member inside of ps_io_ops_t, similar to the way we already have
a clock_sys_t and a mux_sys_t in there.
* Add a void *dependencies argument to the mux_init function that will enable us to
pass arbitrary extra dependencies in.

The latter was chosen because while it is more intrusive, it is slightly more
flexible.

pragma once and for all

Fix whitespace

- remove trailing whitespace
- remove duplicate blank lines
- remove blank lines at end of file

fix licenses

libplatsupport: Refactor tk1 gpio/mux code

This commit refactors the mux and gpio code of the tk1 in the following ways
* Put GPIO code in gpio.c, not mux.c
* Bring back platform generic mux_sys_init and gpio_sys_init functions
* Make GPIO depend upon a mux without the mux initializing the GPIO
* Remove globals and use the provided 'priv' parts of the 'sys' structs
* Require gpio_sys_t be passed to 'gpio_*' functions instead of using
global variables
* Remove circular dependencies in headers and '#ifndef CONFIG_PLAT_TK1's from
generic arm headers

Integrating changes from DARPA repo to trunk

Remove trailing whitespace