alsa-sound: Adjustment for tunnel mode buffer size

- Make necessary adjustments to align the buffer size
  for tunnel mode playback to satisfy the following condition
- Buffer size is a multiple of LCM(1,2,4,6,8)
- Buffer size is aligned to 4k.
CRs-Fixed: 447274, 442365

Change-Id: Ieb188cba6945b96e99bad4ceba4b53112383fd57