1. Add new variable ext_pps_latency_ps in struct spll_stats, using it
to get the ext_pps_latency parameter from ARM(linux).
    2. Change SPLL_STATS_VER to 4, modify the related function.
    3. Modify the Main PLL phase shift in GM mode according to ext_pps_lat-
ency_ps. Calibration are needed if you want to align the PPS out to PPS in.