SystemUI: Add dummy path for stat_sys_signal_none

Change-Id: I0e459002d84aef3f7ddc21134dc56d215de16a51
SystemUI: Re-adjust signal strength icons

Change-Id: Id6dad0800e5e15ec694b24ecb9a88ccc0d4771d8
Merge branch 'cm-12.0' of https://github.com/CyanogenMod/android_frameworks_base into cm-12.0