asoc: Reset the buffer if size is partial or zero

Sometimes during device switch in recording,
observe size 0 is return from DSP due to EOS
handling. For ALSA pcm_read to unblock, buffer
appl_ptr is elapsed without actually updating
the buffer. And userspace copies the stale
data(old buffer) causing issue sometimes.
Reset the buffer for that period_size in
such cases instead of transfer stale data.

Change-Id: I0d3ac133a8d95fad0710586e3e947410a41c9c5a
Signed-off-by: Laxminath Kasam <lkasam@codeaurora.org>