Pull more s390 updates from Heiko Carstens:
 "This is mainly to decouple udelay() and arch_cpu_idle() and simplify
  both of them.

  Summary:

   - Always initialize kernel stack backchain when entering the kernel,
     so that unwinding works properly.

   - Fix stack unwinder test case to avoid rare interrupt stack
     corruption.

   - Simplify udelay() and just let it busy loop instead of implementing
     a complex logic.

   - arch_cpu_idle() cleanup.

   - Some other minor improvements"

* tag 's390-5.11-2' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390/zcrypt: convert comma to semicolon
  s390/idle: allow arch_cpu_idle() to be kprobed
  s390/idle: remove raw_local_irq_save()/restore() from arch_cpu_idle()
  s390/idle: merge enabled_wait() and arch_cpu_idle()
  s390/delay: remove udelay_simple()
  s390/irq: select HAVE_IRQ_EXIT_ON_IRQ_STACK
  s390/delay: simplify udelay
  s390/test_unwind: use timer instead of udelay
  s390/test_unwind: fix CALL_ON_STACK tests
  s390: make calls to TRACE_IRQS_OFF/TRACE_IRQS_ON balanced
  s390: always clear kernel stack backchain before calling functions