dt-bindings: document generic access controllers

Introducing of the generic access controllers bindings for the
access controller provider and consumer devices. Those bindings are
intended to allow a better handling of accesses to resources in a
hardware architecture supporting several compartments.

This patch is based on [1]. It is integrated in this patchset as it
provides a use-case for it.

Diffs with [1]:
	- Rename feature-domain* properties to access-control* to narrow
	  down the scope of the binding
	- YAML errors and typos corrected.
	- Example updated
	- Some rephrasing in the binding description

[1]: https://lore.kernel.org/lkml/0c0a82bb-18ae-d057-562b



Signed-off-by: Oleksii Moisieiev <Oleksii_Moisieiev@epam.com>
Signed-off-by: Gatien Chevallier <gatien.chevallier@foss.st.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>