ARM: Introduce MPS3 AN536

Application Note 536 FPGA image implements the dual Cortex-R52 system
which is extended with interconnect and peripherals to provide an
example design.

Unfortunately, design does't support exclusive access to shareable
memory which is show stopper for SMP support - we enforce shareable
attribute via MPU.

Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>