clk: samsung: exynos5250/5420: Add gate clock for SSS module

This patch adds gating clock for SSS(Security SubSystem)
module on Exynos5250/5420.

Signed-off-by: Naveen Krishna Chatradhi <ch.naveen@samsung.com>
[t.figa: Fixed sort order and group name.]
Signed-off-by: Tomasz Figa <t.figa@samsung.com>