ANDROID: staging: ion: Add an in-kernel interface to request heap info.

Add an API to allow in-kernel clients to request heap ID info.

Test: make
Bug: 149961819

Change-Id: I59d26355115f100a60bcf8ade0e3afa4b89c5d0a
Signed-off-by: Hridya Valsaraju <hridya@google.com>
(cherry picked from commit 0a6517f730e883edb85f5d22b786b927dba7102d)