Audio: Fix for FM off/on delay post SSR

- 8-10sec delay observed when FM is turned off/on from UI post SSR with
  touch tones enabled. If any new input request comes before FM is closed
  post SSR, pcm driver assumes AFE is still active and starts pumping data
  to AFE which is already closed due to SSR causing the delay
- Fix is to close FM session during SSR.

 CRs-Fixed: 673031

Change-Id: I4a55c6ca66d94e633e768b1d40584d5a5782e13e