This commit does the following:
- it introduces additional convenience macros for representing
MPU attributions for no-cacheability, in both ARMv7-M and
ARMv8-M MPU architectures,
- it adds documentation in K_MEM_PARTITION_IS_WRITABLE/CACHEABLE
macros in all macro definitions in the different MPU variants
- it moves the type definition of k_mem_partition_attr_t inside
the architecture-specific MPU headers, so it can be defined
per-architecture. It generalizes app_mem_domain.h, to be able
to work with _any_ (struct) type of k_mem_partition_attr_t.
- it refactors the type of k_mem_partition_attr_t for ARMv8-M
to comply with the MPU register API.
- for NXP MPU, the commit moves the macros for region access
permissions' attributes inside nxp_mpu.h, to align with what
we do for ARM MPU.
Signed-off-by: Ioannis Glaropoulos <Ioannis.Glaropoulos@nordicsemi.no>