Fix problem with awk divide by zero caused by missing {} brackets
Fix problem with awk divide by zero caused by missing {} brackets

Change-Id: Ie20f617c3402e12551066665563ac46f80eaea8e

BUG=chromium-os:8050
TEST=edit boot-complete.conf to produce the failure, and confirm that the login-prompt-ready timestamp still gets created

Review URL: http://codereview.chromium.org/3968008

joshfire/chromiumos-platform-init