Update SubInfo docs for ICC ID / num restrictions in API 30

In Android 11 access to the ICC ID is guarded behind the same access
restrictions as the SIM serial number; the requirements to access the
device phone number have also changed. This commit updates the docs to
reflect that these changes are active starting from API level 30.

Fixes: 159568585
Test: m docs -j
Change-Id: I5ececac6f8dee5281d8bfc6c62408a18c8b3effa