brcm47xx: fix network failsafe indication

Remove the code used on the old switch driver.
The Ethernet drive is loaded as a module and needs some time to get up
therefor we added some wait function.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@39254 3c298f89-4303-0410-b956-a3cf2f4a3e73