dts: bindings: Update Nordic owned memory bindings

This concerns both `nordic,owned-memory` and `nordic,owned-partitions`.

Introduce a property named `nordic,access`, which is meant to replace
the `owner-id` and `perm-*` properties. It allows for describing how
multiple domains should access a single memory region, possibly with
different permissions per owner, but without having to create more than
one DT node for this purpose.

This change is also motivated by updated memory protection requirements
on the nRF54H20, which mandate that a given memory region must only be
reserved by one domain, even if multiple domains can have access to it.
This restriction is now described in the binding itself.

Signed-off-by: Grzegorz Swiderski <grzegorz.swiderski@nordicsemi.no>