ARM: i.MX5x: Add SAHARA clock for i.MX5x CPUs

Patch adds missing Security Accelerator (SAHARA) clock for i.MX5x CPUs.

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

diff --cc Documentation/devicetree/bindings/clock/imx5-clock.txt
Simple merge

diff --cc arch/arm/mach-imx/clk-imx51-imx53.c
Simple merge