sched/rt, s390: Use CONFIG_PREEMPTION

sched/rt, s390: Use CONFIG_PREEMPTION

CONFIG_PREEMPTION is selected by CONFIG_PREEMPT and by CONFIG_PREEMPT_RT.
Both PREEMPT and PREEMPT_RT require the same functionality which today
depends on CONFIG_PREEMPT.

Switch the preemption and entry code over to use CONFIG_PREEMPTION. Add
PREEMPT_RT output to die().

[bigeasy: +Kconfig, dumpstack.c]

Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: Christian Borntraeger <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>