commit 101a68e74fe089b975c407f1bc9359882b05489a upstream

This converts the DaVinci SPI master driver to use GPIO
descriptors for chip select handling.

DaVinci parses the device tree a second time for the chip
select GPIOs (no relying on the parsing already happening
in the SPI core) and handles inversion semantics locally.

We simply drop the extra parsing and set up and move the
CS handling to the core and gpiolib. The fact that the
driver is actively driving the GPIO in the
davinci_spi_chipselect() callback is confusing since the
host does not set SPI_MASTER_GPIO_SS so this should not
ever get called when using GPIO CS. I put in a comment
about this.

This driver also supports instantiation from board files,
but these are all using native chip selects so no problem
with GPIO lines here.

Cc: David Lechner <david@lechnology.com>
Cc: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Cc: Linuxarm <linuxarm@huawei.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: NMark Brown <broonie@kernel.org>
Signed-off-by: NZou Cao <zoucao@linux.alibaba.com>
Reviewed-by: NBaoyou Xie <xie.baoyou@linux.alibaba.com>