SystemUI: Re-adjust signal strength icons

Change-Id: Id6dad0800e5e15ec694b24ecb9a88ccc0d4771d8

Conflicts:
	packages/SystemUI/res/drawable/stat_sys_signal_in.xml
	packages/SystemUI/res/drawable/stat_sys_signal_inout.xml
	packages/SystemUI/res/drawable/stat_sys_signal_out.xml