st-hal: Update latency logging

Previously, the systrace measuring the buffer reads from LSM was
handled by having a single measurement of the 2 second transfer
latency. Now that the keyword start is determined by the preroll,
it is more sensible to measure the LSM buffer reads individually.
Also print FTRT latency and second stage latency logs.

Change-Id: I982ebceeb1695acdb70dd775a71d628b40818a3e
5 files changed