surface pro 4: Add support for Surface Pro 4 Buttons

Surface Pro 4 buttons are managed by a device with _HID "MSHW0040"
different from Surface Pro 3.

This commit adds MSHW0040 to id list to support the Surface Pro 4.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=109871
Signed-off-by: Weng Xuetian <wengxt@gmail.com>
Acked-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>
diff --git a/drivers/platform/x86/surfacepro3_button.c b/drivers/platform/x86/surfacepro3_button.c
index f7dade3..b9c38f6 100644
--- a/drivers/platform/x86/surfacepro3_button.c
+++ b/drivers/platform/x86/surfacepro3_button.c
@@ -1,6 +1,6 @@
 /*
  * power/home/volume button support for
- * Microsoft Surface Pro 3 tablet.
+ * Microsoft Surface Pro 3/4 tablet.
  *
  * Copyright (c) 2015 Intel Corporation.
  * All rights reserved.
@@ -19,9 +19,10 @@
 #include <linux/acpi.h>
 #include <acpi/button.h>
 
-#define SURFACE_BUTTON_HID		"MSHW0028"
+#define SURFACE_PRO3_BUTTON_HID		"MSHW0028"
+#define SURFACE_PRO4_BUTTON_HID		"MSHW0040"
 #define SURFACE_BUTTON_OBJ_NAME		"VGBI"
-#define SURFACE_BUTTON_DEVICE_NAME	"Surface Pro 3 Buttons"
+#define SURFACE_BUTTON_DEVICE_NAME	"Surface Pro 3/4 Buttons"
 
 #define SURFACE_BUTTON_NOTIFY_PRESS_POWER	0xc6
 #define SURFACE_BUTTON_NOTIFY_RELEASE_POWER	0xc7
@@ -54,7 +55,8 @@
  * acpi_driver.
  */
 static const struct acpi_device_id surface_button_device_ids[] = {
-	{SURFACE_BUTTON_HID,    0},
+	{SURFACE_PRO3_BUTTON_HID,    0},
+	{SURFACE_PRO4_BUTTON_HID,    0},
 	{"", 0},
 };
 MODULE_DEVICE_TABLE(acpi, surface_button_device_ids);