Pull ARM updates from Russell King:
 "Included in this update:

   - Florian Fainelli noticed that userspace segfaults caused by the
     lack of kernel-userspace helpers was hard to diagnose; we now issue
     a warning when userspace tries to use the helpers but the kernel
     has them disabled.

   - Ben Dooks wants compatibility for the old ATAG serial number with
     DT systems.

   - Some cleanup of assembly by Nicolas Pitre.

   - User accessors optimisation from Vincent Whitchurch.

   - More robust kdump on SMP systems from Yufen Wang.

   - Sebastian Andrzej Siewior noticed problems with the SMP "boot_lock"
     on RT kernels, and so we convert the Versatile series of platforms
     to use a raw spinlock instead, consolidating the Versatile
     implementation. We entirely remove the boot_lock on OMAP systems,
     where it's unnecessary. Further patches for other systems will be
     submitted for the following merge window.

   - Start switching old StrongARM-11x0 systems to use gpiolib rather
     than their private GPIO implementation - mostly PCMCIA bits.

   - ARM Kconfig cleanups.

   - Cleanup a mostly harmless mistake in the recent Spectre patch in
     4.20 (which had the effect that data that can be placed into the
     init sections was incorrectly always placed in the rodata section)"

* tag 'for-4.21' of git://git.armlinux.org.uk/~rmk/linux-arm: (25 commits)
  ARM: omap2: remove unnecessary boot_lock
  ARM: versatile: rename and comment SMP implementation
  ARM: versatile: convert boot_lock to raw
  ARM: vexpress/realview: consolidate immitation CPU hotplug
  ARM: fix the cockup in the previous patch
  ARM: sa1100/cerf: switch to using gpio_led_register_device()
  ARM: sa1100/assabet: switch to using gpio leds
  ARM: sa1100/assabet: add gpio keys support for right-hand two buttons
  ARM: sa1111: remove legacy GPIO interfaces
  pcmcia: sa1100*: remove redundant bvd1/bvd2 setting
  ARM: pxa/lubbock: switch PCMCIA to MAX1600 library
  ARM: pxa/mainstone: switch PCMCIA to MAX1600 library and gpiod APIs
  ARM: sa1100/neponset: switch PCMCIA to MAX1600 library and gpiod APIs
  ARM: sa1100/jornada720: switch PCMCIA to gpiod APIs
  pcmcia: add MAX1600 library
  ARM: sa1100: explicitly register sa11x0-pcmcia devices
  ARM: 8813/1: Make aligned 2-byte getuser()/putuser() atomic on ARMv6+
  ARM: 8812/1: Optimise copy_{from/to}_user for !CPU_USE_DOMAINS
  ARM: 8811/1: always list both ldrd/strd registers explicitly
  ARM: 8808/1: kexec:offline panic_smp_self_stop CPU
  ...