ARM: exynos_defconfig: Enable CONFIG_LOCKUP_DETECTOR

On enabling CONFIG_LOCKUP_DETECTOR the kernel to act as a watchdog
to detect hard and soft lockups. Enabling CONFIG_LOCKUP_DETECTOR
don't introduce much overhead on exyons SOC.
(CONFIG_LOCKUP_DETECTOR is enabled on multi_v7_defconfig.)

Tested on Exynos5422 ODROID XU3 board.
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Anand Moon <moon.linux@yahoo.com>
Signed-off-by: Kukjin Kim <kgene@kernel.org>

arch/arm/configs/exynos_defconfig

@@ -183,6 +183,7 @@ CONFIG_DETECT_HUNG_TASK=y
 CONFIG_DEBUG_RT_MUTEXES=y
 CONFIG_DEBUG_SPINLOCK=y
 CONFIG_DEBUG_MUTEXES=y
+CONFIG_LOCKUP_DETECTOR=y
 CONFIG_DEBUG_INFO=y
 CONFIG_DEBUG_USER=y
 CONFIG_CRYPTO_SHA256=y