ASoC: msm: qdsp6v2: Fix timestamp query during gapless transition

A query for the current playback position during a gapless transition
must return the most recent playback position until the first buffer
from the next stream has been sent to DSP.

Change-Id: I958a64e74995e6c1d8aaeda2c8cabf9a6d88c143
Bug: 18709620
Signed-off-by: Haynes Mathew George <hgeorge@codeaurora.org>