Make KeyguardStatusView accessible.

Ensure that keyguardstatusview is not null. Also break up update view
controllers so that we can update the keyguardstatusview controller if
it changes.

Bug: 295555276
Test: test to see that status view can be set later than view
inflation.

Change-Id: I1db08a33a98f2523bbca2ebad2bbc115d66b65f5