ARM: imx6sl: Add missing spba clock to clock tree

We are missing spba clock in imx6sl's clock tree, thus add it.

Signed-off-by: Nicolin Chen <Guangyu.Chen@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

diff --cc arch/arm/mach-imx/clk-imx6sl.c
Simple merge

diff --cc include/dt-bindings/clock/imx6sl-clock.h
Simple merge