ARM: SoC updates for 5.18

SoC specific code is generally used for older platforms that don't (yet)
use device tree to do the same things.

 - Support is added for i.MXRT10xx, a Cortex-M7 based microcontroller
   from NXP. At the moment this is still incomplete as other portions
   are merged through different trees.

 - Long abandoned support for running NOMMU ARMv4 or ARMv5 platforms
   gets removed, now the Arm NOMMU platforms are limited to the
   Cortex-M family of microcontrollers

 - Two old PXA boards get removed, along with corresponding driver
   bits.

 - Continued cleanup of the Intel IXP4xx platforms, removing some
   remnants of the old board files.

 - Minor Cleanups and fixes for Orion, PXA, MMP, Mstar, Samsung

 - CPU idle support for AT91

 - A system controller driver for Polarfire