ar71xx: use a common naming scheme for LEDS on wnr2000-v4

It is common that the router provider be used rather than product name.
One can see this in target/linux/ar71xx/base-files/etc/uci-defaults/01_leds

Signed-off-by: Michael J. Bazzinotti <mbazzinotti@gmail.com>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@45630 3c298f89-4303-0410-b956-a3cf2f4a3e73