If you accepted the 2.2 OTA update then your radio is up-to-date. If you
rooted at 2.1 and never updated, then you’ll need to update, either via
the OTA or by downloaded the official release from Google.

The only reason you’d need to worry is if you rooted 2.1 and updated the
radio without updating to 2.2. In that case you’d need to find the old
radio on XDA and downgrade before upgrading to 2.2.