Fix 5479823: black patch was showing before resuming call

- This issue was marked as RelTeamHotIssue

- When Face Unlock is enabled, the black area is shown when going into
  the emergency dialer to prevent the backup lock from showing.
  However, it was doing this even if Face Unlock has already gone to
  the backup method.

- Since the same code is used for returning to a call as is used for
  starting the emergency dialer, it was doing the same thing when
  resuming a call.

- Just had to add a simple check to only display the black area if
  Face Unlock is still running.

- Note that this did *not* cause a problem when Face Unlock was not
  the unlock method.

Change-Id: Icc4deebcb47ceda035ea29c7d976342d3a8a60a7