iproute2: correct license

Source files license headers include the GPL "or ... any later version" language.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/iproute2/iproute2.mk

@@ -9,7 +9,7 @@ IPROUTE2_SOURCE = iproute2-$(IPROUTE2_VERSION).tar.xz
 IPROUTE2_SITE = $(BR2_KERNEL_MIRROR)/linux/utils/net/iproute2
 IPROUTE2_DEPENDENCIES = host-bison host-flex host-pkgconf \
 	$(if $(BR2_PACKAGE_LIBMNL),libmnl)
-IPROUTE2_LICENSE = GPL-2.0
+IPROUTE2_LICENSE = GPL-2.0+
 IPROUTE2_LICENSE_FILES = COPYING
 
 # If both iproute2 and busybox are selected, make certain we win