ASoC: msm: qdsp6v2: fix for pcm_write failure during voip

For VOIP case, hardware pointer is always getting incremented
by fixed pcm count. Because of this, hw_ptr is incrementing much
faster than the actual data consumed by DSP. This leads to
pcm_write failure. Fix is to increment hardware pointer by packet
length of frames consumed by DSP for PCM mode

CRs-Fixed: 811744
Change-Id: I1284bdfbf1e74abd126bcb83b8c3dc80e2efc082
Signed-off-by: Shreyas Nagasandra Chandrasekhar <snagas@codeaurora.org>