leaudio: Fix setting session

We do have assumtion that MEDIA is a default context_type,
but this knowledge is in the currect_context_type_ and if
this is changed, we should take it into account

Bug: 150670922
Tag: #feature
Sponsor: jpawlowski@
Test: manual

Change-Id: I737e45ff1f2ce7280c8657d044cda00552147367