sched/rt, nios2: 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 entry code over to use CONFIG_PREEMPTION.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: nios2-dev@lists.rocketboards.org
Link: https://lore.kernel.org/r/20191015191821.11479-15-bigeasy@linutronix.deSigned-off-by: Ingo Molnar <mingo@kernel.org>

arch/nios2/kernel/entry.S

@@ -365,7 +365,7 @@ ENTRY(ret_from_interrupt)
 	ldw	r1, PT_ESTATUS(sp)	/* check if returning to kernel */
 	TSTBNZ	r1, r1, ESTATUS_EU, Luser_return
 
-#ifdef CONFIG_PREEMPT
+#ifdef CONFIG_PREEMPTION
 	GET_THREAD_INFO	r1
 	ldw	r4, TI_PREEMPT_COUNT(r1)
 	bne	r4, r0, restore_all