ARM: DT changes for 6.0

As usual, the bulk of the changes for the SoC tree are devicetree file
updates, and most of these changes are for 64-bit embedded machines.
As before, there are a ton of style cleanups, and additional hardware
support for existing machines.

Looking only at the new SoC, the notable additions are:

 - A whole family of Broadcom broadband SoCs, both 32-bit and 64-bit:
   BCM63178, BCM63158, BCM4912, BCM6858, BCM6878, BCM6846, BCM63146,
   BCM6856, BCM6855, BCM6756, BCM63148, and BCM6813.
   Each SoC comes with a corresponding reference board.

 - The new NXP i.MX93 SoC, the follow-up to the popular i.MX6 and
   i.MX8 embedded SoCs, now using Cortex-A55 cores and the
   Ethos-U65 NPU.

 - Qualcomm Snapdragon 8cx Gen3 (SC8280XP), the current high end
   of Arm based Laptop SoCs, and its automotive cousin, the
   SA8540P. The SC8280XP is used in the Lenovo Thinkpad X13s
   laptop that also gets added here in addition to the reference
   boards.

 - Allwinner H616, a newer version of the H6 SoC, targeted at
   Set-top-box applications. It comes with dts files for the
   Orange Pi zero2 single-board computer and the X96 Mate
   set-top-box

 - Marvell Prestera 98DX2530 (AlleyCat5), a network switch chip
   in the Armada SoC family based on the Cortex-A55 core.

New machines based on previously supported SoCs include:

 - Several new machines on NXP i.MX platforms: multiple Toradex
   Colibri boards using the "Iris" and "Ixora" carriers,
   DH electronics i.MX8M Plus DHCOM and PDK2, TQ-Systems
   TQMa8MPQL, and phytech phyBOARD-Polis-i.MX8MM.

 - Google Chameleon v3 FPGA board based on Intel Arria10 and
   Stratix 10 Software Virtual platform, both in the SoCFPGA
   platform.

 - Two new wireless devices based on Broadcom SoCs:
   The Asus GT-AX6000 Router and the Cisco Meraki MR26 access point

 - Improved Chromebook support for both the Mediatek and Qualcomm
   SoC families brought added machines: Acer Chromebook 514 (MT8192),
   Acer Chromebook Spin 513 (MT8195) and a couple of SC7180 based
   machines including the Lenovo IdeaPad Chromebook Duet 3.

 - Xiaomi Mi Mix2s, LG G7 and LG V35 are mobile phones based on
   Qualcomm SDM845, while Mi 5s Plus is based on MSM8996.

 - Finally, there are a few development board on other chips:
   PCB8309 (Microchip lan966x), Radxa Rock Pi S (Rockchips RK3308)
   DH DRC Compact (ST STM32MP1) and Inforce IFC6560 (Qualcomm
   SDM660)