gpio-button-hotplug: add volume button handling

This is used by PISEN WMB001N.

Signed-off-by: Chuanhong Guo <gch981213@gmail.com>
(cherry picked from commit 11182349e1f31f873ebddd69d6b87dec638eaabf)

package/kernel/gpio-button-hotplug/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 include $(INCLUDE_DIR)/kernel.mk
 
 PKG_NAME:=gpio-button-hotplug
-PKG_RELEASE:=2
+PKG_RELEASE:=3
 PKG_LICENSE:=GPL-2.0
 
 include $(INCLUDE_DIR)/package.mk

package/kernel/gpio-button-hotplug/src/gpio-button-hotplug.c

@@ -95,6 +95,8 @@ static struct bh_map button_map[] = {
 	BH_MAP(KEY_RESTART,		"reset"),
 	BH_MAP(KEY_RFKILL,		"rfkill"),
 	BH_MAP(KEY_VIDEO,		"video"),
+	BH_MAP(KEY_VOLUMEDOWN,		"volume_down"),
+	BH_MAP(KEY_VOLUMEUP,		"volume_up"),
 	BH_MAP(KEY_WIMAX,		"wwan"),
 	BH_MAP(KEY_WLAN,		"wlan"),
 	BH_MAP(KEY_WPS_BUTTON,		"wps"),