Android patch: Remove javadoc about the unsupported "tz" extension

The feature isn't critical because the existing API in the Calendar
class has allowed the developer to set a TimeZone object and the
DateFormat has the setCalendar() method.

Bug: 205685050
Test: m docs
Change-Id: If3e55226f9d15fe3f2e429fac20b68e1555ba789
1 file changed