intel_mid_powerbtn: add power button driver for Medfield platform (#3)

The power button is connected to MSIC on Medfield, we will get two
interrupts from IOAPIC when pressing or releasing the power button.

Signed-off-by: Hong Liu <hong.liu@intel.com>
[Minor fixes as noted by Dmitry]
Signed-off-by: Alan Cox <alan@linux.intel.com>
Acked-by: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Matthew Garrett <mjg@redhat.com>

drivers/platform/x86/Kconfig

@@ -616,6 +616,14 @@ config GPIO_INTEL_PMIC
 	  Say Y here to support GPIO via the SCU IPC interface
 	  on Intel MID platforms.
 
+config INTEL_MID_POWER_BUTTON
+	tristate "power button driver for Intel MID platforms"
+	depends on INTEL_SCU_IPC
+	help
+	  This driver handles the power button on the Intel MID platforms.
+
+	  If unsure, say N.
+
 config RAR_REGISTER
 	bool "Restricted Access Region Register Driver"
 	depends on PCI && X86_MRST