broadcom-wl: fix led support

Some devices have an nvram setting, which make broadcom-wl turn of the 
led all the time. When the driver is switched on and we find such a 
setting we replace it with a better value.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>


git-svn-id: svn://svn.openwrt.org/openwrt/trunk@41518 3c298f89-4303-0410-b956-a3cf2f4a3e73