treewide: unify OpenWrt hosted source via @OPENWRT

Multiple sources are hosted on OpenWrts source server only. The source
URLs to point to the server vary based on different epochs in OpenWrts
history.

Replace all by @OPENWRT which is an "empty" mirror, therefore using the
fallback servers sources.cdn.openwrt.org and sources.openwrt.org.

Signed-off-by: Paul Spooren <mail@aparcar.org>

package/firmware/b43legacy-firmware/Makefile

@@ -12,7 +12,7 @@ PKG_VERSION:=3.130.20.0
 PKG_RELEASE:=1
 
 PKG_SOURCE:=wl_apsta-$(PKG_VERSION).o
-PKG_SOURCE_URL:=https://downloads.openwrt.org/sources
+PKG_SOURCE_URL:=@OPENWRT
 PKG_HASH:=7dba610b1d96dd14e901bcbce14cd6ecd1b1ac6f5c0035b0d6b6dc46a7c3ef90
 
 include $(INCLUDE_DIR)/package.mk

package/firmware/lantiq/dsl-vrx200-firmware-xdsl/Makefile

@@ -10,7 +10,7 @@ PKG_NAME:=dsl_vr9_firmware_xdsl
 PKG_VERSION:=05.08.01.08.01.06_05.08.00.0B.01.01_osc
 PKG_RELEASE:=1
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
-PKG_SOURCE_URL:=http://mirror2.openwrt.org/sources
+PKG_SOURCE_URL:=@OPENWRT
 PKG_HASH:=44cd94130571fe42dfa8f0f9d44597d104e9e77962617fe38646b7a0b4184a2b
 PKG_BUILD_DEPENDS:=bsdiff/host