Start bridge before running hostapd

Start and configure the bridge to disable STP before starting
hostapd.  This gets rid of a problem we've been having where
EAPOL fails on the first attempt for some WPA modes in the
testbed.

TEST=SecMat
BUG=chromium-os:10181

Change-Id: I6981cc3abedc430aa7a80deac0eb1cb3c65416c8

Review URL: http://codereview.chromium.org/5689002
1 file changed