nbd: update icense information

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/nbd/nbd.mk

@@ -10,6 +10,7 @@ NBD_SITE = http://downloads.sourceforge.net/project/nbd/nbd/$(NBD_VERSION)
 NBD_CONF_OPT = $(if $(BR2_LARGEFILE),--enable-lfs,--disable-lfs)
 NBD_DEPENDENCIES = libglib2
 NBD_LICENSE = GPLv2
+NBD_LICENSE_FILES = COPYING
 
 ifeq ($(BR2_TOOLCHAIN_USES_UCLIBC),y)
 # We have linux/falloc.h