This patch add basic building blocks for nrf9P60.
It also includes a secure bootloader which forwards all
possible peripherals that are user selectable to become
non-secure. After configuring Flash, RAM and peripherals
the secure bootloader will jump to the non-secure domain
where MicroPython is placed.
The minimum size of a secure boot has to be a flash
block of 32Kb, hence why the linker scripts are
offsetting the main application this much.
The RAM offset is set to 128K, to allow for later
integration of Nordic Semiconductor's BSD socket
library which reserves the range 0x20010000 - 0x2001FFFF.
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