Consider all phones when deciding if TTY is changeable during call

Consider VoLTE TTY support on all phones when deciding if TTY should be
changeable during an ongoing call.

Current behavior is to only look at the default phone, which might cause
incorrect behavior in multi sim scenario since an incoming call can be
received on any phone.

Bug: 148260911
Test: atest TeleServiceTests
Change-Id: I49762d92fe77ff869a59d55f79408c907e3f9d7c
1 file changed