[DO NOT MERGE] Update security string to 2018-02-01 for mnc-dev bug:70348883 am: 74f105c16f am: 6545915c0b am: 567d926508 am: 06602d3239  -s ours am: 3980822dff am: 5d59b6650b
am: ca5b4e7969

Change-Id: Ib02b7dc53426a1ee0ad051c1c31997c9b8ff2dfc