gpio: mcp230xx: Introduce new driver

Introduce driver for I2C based MCP230xx GPIO chips, which are
quite common and already well supported by the Linux kernel.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 09695f6..4a89c1a 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -179,6 +179,16 @@
 	help
 	  Support for the LPC32XX GPIO driver.
 
+config MCP230XX_GPIO
+	bool "MCP230XX GPIO driver"
+	depends on DM
+	help
+	  Support for Microchip's MCP230XX I2C connected GPIO devices.
+	  The following chips are supported:
+	   - MCP23008
+	   - MCP23017
+	   - MCP23018
+
 config MSCC_SGPIO
 	bool "Microsemi Serial GPIO driver"
 	depends on DM_GPIO && SOC_VCOREIII