Recovery: add interface of touch virtual key

If you want use Touch Recovery, set BOARD_TOUCH_VIRTUAL_KEY_RECOVERY := true in BoardConfig.mk of your device.
Recovery use 480 virtual key by default, set TARGET_SCREEN_WIDTH := 720 or 1080 for your own.

Change-Id: Ic73598b1bb78889f047f7ce2c8d54efbf54a9191