Reduce native heap usage of QSCarrier#updateState.

Avoid unnecessary calls to ImageView#setImageDrawable with a new Signal
Drawable.

Fixes: 144098259
Test: While running native heap profiler, change the mobile network
level in demo mode. Then, look at space used by QSCarrier#updateState.

Change-Id: Id640cbedb452bdc9e7fd4da4b28c316fd1353c28
1 file changed