gpio: amdpt: Convert to use gpio-generic

Use gpio-generic to simplify this driver.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Tested-by: YD Tseng <Yd_Tseng@asmedia.com.tw>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 927be87..6d6015f 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -122,6 +122,7 @@
 config GPIO_AMDPT
 	tristate "AMD Promontory GPIO support"
 	depends on ACPI
+	select GPIO_GENERIC
 	help
 	  driver for GPIO functionality on Promontory IOHub
 	  Require ACPI ASL code to enumerate as a platform device.