ARM: dts: add dt node for sss module for exynos5250/5420

This patch adds the device tree node for SSS module
found on Exynos5420 and Exynos5250

Signed-off-by: Naveen Krishna Chatradhi <ch.naveen@samsung.com>
Reviewed-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>