Remove some (unused, non-public) phone-related status bar notification icons

Status bar icons really belong to specific apps (not the framework), so the
various stat_sys_phone_call* and stat_sys_vp_phone_call* icons should have
never been part of the framework in the first place.

As of change https://android-git.corp.google.com/g/56881 the phone app now has
its own copies of all these icons, so it's now safe to remove the non-public
ones(*) from frameworks/base.

(*) Unfortunately a few of these icons were accidentally added to public.xml
    at some point, so we'll never be able to get rid of those ones.
    This change only removes the private resources.

Change-Id: If9ecf7b7568b5086c6ed1e5d4b69518fb41f1516