pinctrl: Add SX150X GPIO Extender Pinctrl Driver

Since the I2C sx150x GPIO expander driver uses platform_data to manage
the pins configurations, rewrite the driver as a pinctrl driver using
pinconf to get/set pin configurations from DT or debugfs.

The pinctrl driver is functionnally equivalent as the gpio-only driver
and can use DT for pinconf. The platform_data confirmation is dropped.

This patchset removed the gpio-only driver and selects the Pinctrl driver
config instead. This patchset also migrates the gpio dt-bindings to pinctrl
and add the pinctrl optional properties.

The driver was tested with a SX1509 device on a BeagleBone black with
interrupt support and on an X86_64 machine over an I2C to USB converter.

This is a fixed version that builds and runs on non-OF platforms and on
arm based OF. The GPIO version is removed and the bindings are also moved
to the pinctrl bindings.

Changes since v2
 - rebased on v4.9-rc1
 - removed MODULE_DEVICE_TABLE as in upstream bb411e771b0e
   ("gpio: sx150x: fix implicit assumption module.h is present")

Changes since v1
 - Fix Kconfig descriptions on pinctrl and gpio
 - Fix Kconfig dependency
 - Remove oscio support for non-789 devices
 - correct typo in dt bindings
 - remove probe reset for non-789 devices

Changes since RFC
 - Put #ifdef CONFIG_OF/CONFIG_OF_GPIO to remove OF code for non-of platforms
 - No more rely on OF_GPIO config
 - Moved and enhanced bindings to pinctrl bindings
 - Removed gpio-sx150x.c
 - Temporary select PINCTRL_SX150X when GPIO_SX150X
 - Temporary mark GPIO_SX150X as deprecated

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Tested-by: Peter Rosin <peda@axentia.se>
Acked-by: Rob Herring <robh@kernel.org>
ested-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 26ee00f..db3f7aa 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -781,16 +781,13 @@
 	  platform-neutral GPIO calls.
 
 config GPIO_SX150X
-	bool "Semtech SX150x I2C GPIO expander"
-	depends on I2C=y
-	select GPIOLIB_IRQCHIP
+	bool "Semtech SX150x I2C GPIO expander (deprecated)"
+	depends on PINCTRL && I2C=y
+	select PINCTRL_SX150X
 	default n
 	help
-	  Say yes here to provide support for Semtech SX150-series I2C
-	  GPIO expanders. Compatible models include:
-
-	  8 bits:  sx1508q
-	  16 bits: sx1509q
+	  Say yes here to provide support for Semtech SX150x-series I2C
+	  GPIO expanders. The GPIO driver was replaced by a Pinctrl version.
 
 config GPIO_TPIC2810
 	tristate "TPIC2810 8-Bit I2C GPO expander"