Input: add powerkey driver for HISI 65xx SoC

This driver provides a input driver for the power button on the
HiSi 65xx SoC for boards like HiKey.

This driver was originally by Zhiliang Xue <xuezhiliang@huawei.com>
then basically rewritten by Jorge, but preserving the original
module author credits.

Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
[jstultz: Reworked commit message, folded in other fixes/cleanups
from Jorge, implemented some larger cleanups suggested by DmitryT]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
index 27d6da0..efb0ca8 100644
--- a/drivers/input/misc/Kconfig
+++ b/drivers/input/misc/Kconfig
@@ -810,4 +810,13 @@
 	  To compile this driver as a module, choose M here: the
 	  module will be called drv2667-haptics.
 
+config INPUT_HISI_POWERKEY
+	tristate "Hisilicon PMIC ONKEY support"
+	depends on ARCH_HISI || COMPILE_TEST
+	help
+	  Say Y to enable support for PMIC ONKEY.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called hisi_powerkey.
+
 endif