brcm47xx: fix switch handling

brcm47xx: fix switch handling

This fixes some problems with the switch handling

 * It now send the messages again to indicate a button for failsafe mode should be pressed
 * it does not leak packages between wan and lan any more
 * the switch works again in normal mode

The Ethernet connection has to be up when the switch driver switch-robo
is insmoded therefor we just do it again.
Explicitly set enable_vlan to prevent leaking packages.

This should close #13869, #13868 and #13716

SVN-Revision: 37286