ASoC: msm: qdsp6v2: Don't register to modem for SSR callbacks

Voice driver doesn't create any sessions related to voice call
on modem and hence there is no clean up on APSS is required
when modem SSR is triggered. Cleanup the code in voice driver
which is executed during modem SSR.

CRs-Fixed: 955696
Change-Id: I7536162e49b0eb56f63e7c8e59e0c050123c05fe
Signed-off-by: Venkata Narendra Kumar Gutta <vgutta@codeaurora.org>