ASoC: msm: reduce period_bytes_min for voice call

- Allow smaller buffer size for voice call to
  comply with MR1 audio HAL

Change-Id: Iaffca753ad07889b08ae4b6154e8d596950a979e
Signed-off-by: Mingming Yin <mingming@codeaurora.org>
(cherry picked from commit 8530609eefc16add493bce6fbb55500e60b6bc9f)