This switch to use BIT(n) instead of (1 << n) which is less
to the point. Most GPIO drivers do this to avoid mistakes.
Also switch from using <linux/gpio.h> to the apropriate
<linux/gpio/driver.h> include.
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>