spi/gpio: start with CS non-active

The chip select line was configured as output with the initial value
being active explicitly. It was later deasserted during
spi_bitbang_setup() without any clock activity in between. So it makes
no sense to activate the device at all and the chip select line can
better start non-active.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>