Merge remote-tracking branch 'upstream/openwrt-18.06' into develop

diff --cc target/linux/ar71xx/base-files/etc/board.d/02_network
Simple merge

diff --cc target/linux/ar71xx/base-files/lib/ar71xx.sh
Simple merge

diff --cc target/linux/ar71xx/base-files/lib/upgrade/platform.sh
Simple merge

diff --cc target/linux/ar71xx/config-4.9
Simple merge

diff --cc target/linux/ar71xx/files/arch/mips/ath79/Kconfig.openwrt
Simple merge

diff --cc target/linux/ar71xx/files/arch/mips/ath79/Makefile
Simple merge

diff --cc target/linux/ar71xx/files/arch/mips/ath79/machtypes.h
Simple merge

diff --cc target/linux/ar71xx/generic/config-default
Simple merge

diff --cc target/linux/ar71xx/image/generic.mk
Simple merge