ARM: EXYNOS: do not allow cpuidle registration for exynos5420

Exynos5420 is big.Little Soc. It uses cpuidle-big-litle generic cpuidle driver.
Hence do not allow exynos cpuidle driver registration for Exynos5420.
Signed-off-by: NChander Kashyap <chander.kashyap@linaro.org>
Reviewed-by: NTomasz Figa <t.figa@samsung.com>
Acked-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: NKukjin Kim <kgene.kim@samsung.com>

arch/arm/mach-exynos/exynos.c

@@ -298,7 +298,9 @@ static void __init exynos_dt_machine_init(void)
 	if (!IS_ENABLED(CONFIG_SMP))
 		exynos_sysram_init();
 
-	exynos_cpuidle_init();
+	if (!of_machine_is_compatible("samsung,exynos5420"))
+		exynos_cpuidle_init();
+
 	exynos_cpufreq_init();
 
 	of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);