base: fix NetworkTraffic indicator for MSIM devices

On MSIM devices, upon activating dual SIM, SystemUI
throws NPE and crashes constantly at boot.

Change-Id: I669ac7697ef02243f01af76d260c0d4592cef5b2
SystemUI: MSim: hide subs label on KeyGuard

This is already displayed on the top-left corner

Change-Id: If671e7875693143a721f37cd090aa28b2512800e