Set the frame type to AMR_NO_DATA when the bad frame indicator is set

Previously the bfi parameter was unused.

Some better error concealment might be possible if hooking into
decoder internals at lower levels though.
Handle the bad frame indicator parameter in the amr-wb decoder as well

For amr-wb, we could either set 15 (NO_DATA) or 14 (SPEECH_LOST),
they seem to behave mostly the same in a quick test.