spi: document CS setup, hold & inactive times in header

This change documents the CS setup, host & inactive times. They were
omitted when the fields were added, and were caught by one of the build
bots.

Fixes: 25093bde ("spi: implement SW control for CS times")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20191023070046.12478-1-alexandru.ardelean@analog.comSigned-off-by: Mark Brown <broonie@kernel.org>

include/linux/spi/spi.h

@@ -407,6 +407,11 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv)
  *	     controller has native support for memory like operations.
  * @unprepare_message: undo any work done by prepare_message().
  * @slave_abort: abort the ongoing transfer request on an SPI slave controller
+ * @cs_setup: delay to be introduced by the controller after CS is asserted
+ * @cs_hold: delay to be introduced by the controller before CS is deasserted
+ * @cs_inactive: delay to be introduced by the controller after CS is
+ *	deasserted. If @cs_change_delay is used from @spi_transfer, then the
+ *	two delays will be added up.
  * @cs_gpios: LEGACY: array of GPIO descs to use as chip select lines; one per
  *	CS number. Any individual value may be -ENOENT for CS lines that
  *	are not GPIOs (driven by the SPI controller itself). Use the cs_gpiods