Telephony: fix tdsdma asu invalid value

The magic value for invalid asu is "99", not "255". This error is causing the value validity checks to fail incorrectly, fixit.

Change-Id: Ief816eb577ccf371b3c85df1fe9515eb0bfb3f06
(cherry picked from commit 42d38835f717191147e57e17fec693e0ef446d33)