ARM: exynos_defconfig: Enable LEDS for Odroid-XU3/XU4

Odroid XU3 family boards come with RGB LEDs. Enabling LEDS_GPIO and
LEDS_PWM allows monitoring the board alive state (heartbeat) and
MMC/SDcard IO usage.

Signed-off-by: Anand Moon <linux.amoon@gmail.com>
Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>
[k.kozlowski: Rewritten the commit message]
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Kukjin Kim <kgene@kernel.org>