SystemUI: Fix percentage charging color does not apply

How to reproduce:
Set colors to default. Try to set only charging color.

Result:
- nothing happens when you try to charge and it is out of the max and min levels

Expected behaviour
- user choosen color applies if the user charges and it is outside the max min levels

The JB style icon which was recently introduced broke the logic completely. Clean it a
bit up and apply the colors correctly depending on the choosen style.

NOTE for the future: We have since the JB style patch 2 different behaviours....text has now indication
during charge when it is outside the min max levels. All circle styles do not have this
indication. Nothing big but we are usually consistent and should think about it.

Whatever functioniallity wise it is fixed

Change-Id: I5029d09fbf1a7e4181b082ad55d9607bcf8a63cc
More code clean up after HeadsUp

Change-Id: Id8c5d94a97ed59775051d4bdca87c04ec229b95f