- add DEF_CLK_1B to define clocks using one bit gate
- add cko1 clock and set ahb as the default parent

imx6q-sabrelite board use it as audio codec clock.
Signed-off-by: NRichard Zhao <richard.zhao@linaro.org>
Signed-off-by: NShawn Guo <shawn.guo@linaro.org>