ar71xx: fix WLAN 5 GHz LED init on dir-825-c1

Fixes the 5 GHz LED.

The same function has no effect on the 2.4 GHz LED at all, so we might
as well remove it.

Signed-off-by: Sebastian Kemper <sebastian_ml@gmx.net>
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

SVN-Revision: 38482