dt-bindings: Remove leading zeros from bindings notation

Improve the binding example by removing all the leading zeros to fix the
following dtc warnings:

Warning (unit_address_format): Node /XXX unit name should not have leading 0s

Converted using the following command:

perl -p -i -e 's/\@0+([0-9a-f])/\@$1/g' `find ./Documentation/devicetree/bindings "*.txt"`

Some unnecessary changes were manually fixed.

Signed-off-by: Marco Franchi <marco.franchi@nxp.com>
Signed-off-by: Rob Herring <robh@kernel.org>

gpio: syscon: reuse for keystone 2 socs

On Keystone SOCs, ARM host can send interrupts to DSP cores using the
DSP GPIO controller IP. Each DSP GPIO controller provides 28 IRQ signals for
each DSP core. This is one of the component used by the IPC mechanism used
on Keystone SOCs.

Keystone 2 DSP GPIO controller has specific features:
- each GPIO can be configured only as output pin;
- setting GPIO value to 1 causes IRQ generation on target DSP core;
- reading pin value returns 0 - if IRQ was handled or 1 - IRQ is still
pending.

This patch updates gpio-syscon driver to be reused by Keystone 2 SoCs,
because the Keystone 2 DSP GPIO controller is controlled through Syscon
devices and, as requested by Linus Walleij, such kind of GPIO controllers
should be integrated with drivers/gpio/gpio-syscon.c driver.

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>