arm: Enable the ARM MPU on the NXP i.MX RT SoC and board

Unlike other NXP SoCs currently in Zephyr, the mimxrt1052 has the ARM
MPU rather than the NXP MPU. Start out by enabling it with a simple set
of memory regions for "flash" (ITCM), "ram" (DTCM), and the peripheral
buses. More regions will need to be added when we implement support for
external memories.

Tested with:
- samples/mpu/mpu_stack_guard_test
- tests/kernel/mem_protect/protection

Signed-off-by: Maureen Helm <maureen.helm@nxp.com>