(3/6) bcm57xx: preinit

(3/6) bcm57xx: preinit

This patch allows the bcm57xx module to work correctly with failsafe mode.

insmod doesn't return an error when a module loads but doesn't detect a switch.
I added the check_module function to load the module, then make sure
it doesn't just exit immediately.  This allows preinit to only attempt to
load the bcm57xx module when switch-robo and switch-adm dont detect a switch.

The activate_gpio parameter to bcm57xx simply instructs the module to attempt
to activate the switch via gpio before probing for the switch.

Tested on wrt350n.

Signed-off-by: Ben Pfountz <netprince (at) vt (dot) edu>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@11468 3c298f89-4303-0410-b956-a3cf2f4a3e73