ASoC: msm: qdsp6v2: requeue read buffers in mmap device switch

When device switch happens, ASM might return a 0 length
buffer. For MMAP style capture cases, buffers need to be
re-queued at the event handler for this case, otherwise
ASM will have no buffers to read data into after the
device is over successful.

CRs-fixed: 700614
Change-Id: I2b8930a3058bbe3979405d5de04d3371291db42d
Signed-off-by: Banajit Goswami <bgoswami@codeaurora.org>