Use DTMF stream instead of BT SCO for ToneGenerator

The ToneGenerator should not be created for STREAM_BLUETOOTH_SCO.
Whenever user does that, replacing with STREAM_DTMF

Flag: EXEMPT bugfix
Test: repro in bug
Bug: 361576207
Change-Id: I0ebfe28bf2ec41ee7e31ced49d1c60da57fb4b53