iproute2: use URL alias

Drop hardcoded URL and use the @KERNEL alias.

Signed-off-by: Zoltan HERPAI <wigyori@uid0.hu>

package/network/utils/iproute2/Makefile

@@ -12,7 +12,7 @@ PKG_VERSION:=4.0.0
 PKG_RELEASE:=1
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.xz
-PKG_SOURCE_URL:=http://kernel.org/pub/linux/utils/net/iproute2/
+PKG_SOURCE_URL:=@KERNEL/linux/utils/net/iproute2/
 PKG_MD5SUM:=3adc263ade4ee76c35032e8f50b54108
 PKG_BUILD_PARALLEL:=1
 PKG_LICENSE:=GPL-2.0