usbutils: add license tag

show the license for this package in opkg

Signed-off-by: Florian Eckert <Eckert.Florian@googlemail.com>

package/utils/usbutils/Makefile

@@ -9,11 +9,13 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=usbutils
 PKG_VERSION:=007
-PKG_RELEASE:=3
+PKG_RELEASE:=4
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.bz2
 PKG_SOURCE_URL:=@KERNEL/linux/utils/usb/usbutils
 PKG_MD5SUM:=a6bd63d5c44cebb717a960eae22a3ca9
+PKG_LICENSE:=GPL-2.0
+PKG_LICENSE_FILES:=COPYING
 
 USB_IDS_VERSION:=2016-03-03
 USB_IDS_MD5SUM:=273596b6ee101b1df454827cfa87dff8