Introduce support for TL-WDR3500

Support for the TL-WDR3500 is introduced to Gluon by cherry-picks from OpenWrt Barrier Breaker.
Additionally the kernel config was patched, as openwrt/target/linux/ar71xx/config-3.3 is not used.
TL-WDR3500 added to profiles.

This is tested on one TL-WDR3500 so far.