Limit keyguard views on alt displays

When casting or on other displays, the keyguard has always limited the
information shown when locked. Don't show the smartspace and icons on
these alternate displays

Fixes: 196175396
Test: manual (cast to nest display device)
Change-Id: Ied1ecff9103d8539f075785409d2951a1be21ab2
(cherry picked from commit 893286a5)