clocksource/drivers/arm_arch_timer: Extract elf_hwcap use to arch-helper

Different mechanisms are used to test and set elf_hwcaps between ARM
and ARM64, this results in the use of ifdeferry in this file when
setting/testing for the EVTSTRM hwcap.

Let's improve readability by extracting this to an arch helper.

Signed-off-by: Andrew Murray <andrew.murray@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 5c69c9a..3c8afcd 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -804,14 +804,7 @@ static void arch_timer_evtstrm_enable(int divider)
 	cntkctl |= (divider << ARCH_TIMER_EVT_TRIGGER_SHIFT)
 			| ARCH_TIMER_VIRT_EVT_EN;
 	arch_timer_set_cntkctl(cntkctl);
-#ifdef CONFIG_ARM64
-	cpu_set_named_feature(EVTSTRM);
-#else
-	elf_hwcap |= HWCAP_EVTSTRM;
-#endif
-#ifdef CONFIG_COMPAT
-	compat_elf_hwcap |= COMPAT_HWCAP_EVTSTRM;
-#endif
+	arch_timer_set_evtstrm_feature();
 	cpumask_set_cpu(smp_processor_id(), &evtstrm_available);
 }
 
@@ -1040,11 +1033,7 @@ static int arch_timer_cpu_pm_notify(struct notifier_block *self,
 	} else if (action == CPU_PM_ENTER_FAILED || action == CPU_PM_EXIT) {
 		arch_timer_set_cntkctl(__this_cpu_read(saved_cntkctl));
 
-#ifdef CONFIG_ARM64
-		if (cpu_have_named_feature(EVTSTRM))
-#else
-		if (elf_hwcap & HWCAP_EVTSTRM)
-#endif
+		if (arch_timer_have_evtstrm_feature())
 			cpumask_set_cpu(smp_processor_id(), &evtstrm_available);
 	}
 	return NOTIFY_OK;