arm64: fix typo in entry.S

Commit 6468178 (arm64: let the core code deal with preempt_count)
changed the code, but left the comments unchanged, fix it.

Signed-off-by: Neil Zhang <zhangwm@marvell.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/kernel/entry.S

@@ -316,7 +316,7 @@ el1_irq:
 
 #ifdef CONFIG_PREEMPT
 	get_thread_info tsk
-	ldr	w24, [tsk, #TI_PREEMPT]		// restore preempt count
+	ldr	w24, [tsk, #TI_PREEMPT]		// get preempt count
 	cbnz	w24, 1f				// preempt count != 0
 	ldr	x0, [tsk, #TI_FLAGS]		// get flags
 	tbz	x0, #TIF_NEED_RESCHED, 1f	// needs rescheduling?