ASoC: msm: qdsp6v2: update rtac driver with asm handle

rtac driver uses the asm session handle to communicate with DSP
this handle is supplied to rtac driver in q6asm_audio_client_alloc
function. But the rtac driver is not updated when the asm session
is de-allocated. This change is about updating rtac driver with
asm session handle during q6asm_audio_client_free.

Change-Id: I10bab5830d8e29d17907511c757c4d2bcf09c0cc
Signed-off-by: Srikanth Uyyala <suyyala@codeaurora.org>