[chromeos-init] mount debugfs no{dev,exec,suid}

Autotest update at <https://gerrit.chromium.org/gerrit/#/c/41845>

BUG=chromium-os:32632
TEST=platform_FilePerms,adhoc
build, boot, 'mount | grep debugfs'

Change-Id: Icaf245fb319315020127a2529f42d73e7d9e5b1f
Signed-off-by: Elly Fong-Jones <ellyjones@chromium.org>
Previous-Reviewed-on: https://gerrit.chromium.org/gerrit/41844
(cherry picked from commit 913f9d9d9a70ba431124b1e5c05f6a6abed95e33)
Reviewed-on: https://gerrit.chromium.org/gerrit/42683
Tested-by: Jorge Lucangeli Obes <jorgelo@chromium.org>
diff --git a/chromeos_startup b/chromeos_startup
index 3439c4c..ce316f0 100755
--- a/chromeos_startup
+++ b/chromeos_startup
@@ -37,7 +37,7 @@
 
 mount -n -t tmpfs -o nodev,noexec,nosuid tmp /tmp
 # Mount debugfs as crossystem requires chromeos_arm driver interface.
-mount -n -t debugfs debugfs /sys/kernel/debug
+mount -n -t debugfs -o nodev,noexec,nosuid debugfs /sys/kernel/debug
 
 # bootstat writes timings to both tmpfs and debugfs.
 bootstat pre-startup