Removing static reference from sUnknown

Removing static reference from field sUnknown
allows framework to handle properly resources.
Current implementation holds an instance of
sUnknown, final user sees "Unknown" field on the
IMEI SV [ Menu > About > Status ] even if the
language set is other than english.

Change-Id: I6345f578577e631782c0598bfa44ff4de04c6261