Fix GTK rekeying interval test

The hostapd config says that the wpa_group_rekey kvp is used for
setting the time interval for gtk.  The test should probably be using this.

BUG=None
TEST=Run SecMat test. Verify "wlan0: WPA: Group rekeying completed with..."
      shows up in the logs.

Change-Id: I7ed21634ad50100ef44179c43d0c3f66cb546d2a
Reviewed-on: https://gerrit.chromium.org/gerrit/24415
Reviewed-by: Paul Stewart <pstew@chromium.org>
Commit-Ready: Stanley Wong <stanleyw@chromium.org>
Tested-by: Stanley Wong <stanleyw@chromium.org>
1 file changed