ASoC: msm8996: overwrite pmqos request for low latency playback

During low latency playback testing, it was found that allowing
CPU to enter L2 power collapse(PC) state has adverse effect on power
consumption. This adverse effect can be avoided by voting lower
latency requirement through PM_QOS framework. ALSA core framework
votes on behalf of client driver. However, latency value is derived
based on 75% of period size and does not provide hook for client
driver to customize ratio. This latency value on MSM8996 would not
allow CPU to enter L2 PC state with 5ms buffer size. In consideration
of avoiding change in ALSA core framework and not impacting other
existing use case behavior, update MSM8996 machine driver to
overwrite pmqos latency value only for low latency PCM device.

Change-Id: I21605d077805c039039c95d1b58443ee1d63e2b1
Signed-off-by: Patrick Lai <plai@codeaurora.org>