SystemUI: RAM bar view optimizations

findViewById() was being called every time updateSettings()
was being called. Instead, let's instantiate them once, and 
remove calls to updateSettings() since it will be called 
on its own when the setting values change.

Change-Id: Iaa02343caccb615921219be2a56b3bac4f3263b9
Signed-off-by: Roman Birg <romanbirg@gmail.com>
Merge "SystemUI: RAM bar view optimizations" into jb-mr1
Merge changes I7d389b9a,Iaa02343c into jb-mr1

* changes:
  Merge "SystemUI: RAM bar view optimizations" into jb-mr1
  SystemUI: RAM bar view optimizations