gpio: mcp23s08: Select REGMAP/REGMAP_I2C to fix build error

This driver now using devm_regmap_init/devm_regmap_init_i2c, so it needs
to select REGMAP/REGMAP_I2C accordingly.

Fixes: ("3d84fdb3 gpio: mcp23s08: use regmap")
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Acked-By: Sebastian Reichel <sre@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/Kconfig

@@ -1213,6 +1213,8 @@ config GPIO_MCP23S08
 	tristate "Microchip MCP23xxx I/O expander"
 	depends on OF_GPIO
 	select GPIOLIB_IRQCHIP
+	select REGMAP_I2C if I2C
+	select REGMAP if SPI_MASTER
 	help
 	  SPI/I2C driver for Microchip MCP23S08/MCP23S17/MCP23008/MCP23017
 	  I/O expanders.