ARM: dts: nomadik: Set up the CS GPIO right

ARM: dts: nomadik: Set up the CS GPIO right

Now that the SPI GPIO driver knows how to handle these
chip select GPIOs and we get nasty messages about the
core having to enforce active low on the GPIO, fix this
up by actually requesting the CS GPIO line as active
low.

Link: https://lore.kernel.org/r/20190813072731.4558-1-linus.walleij@linaro.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>