I got that RAM stick working when I changed the fourth byte of SPD from from mini-UDIMM (0x06) to SO-DIMM (0x03) and its working fine... But still I am curious why mini-UDIMM didn't work out. Perhaps this form factor was not supported by FSP?

Another thing I observed that the call to FSP_FSP_INIT takes 7-8 seconds to return back. Is that expected? What could be the possible ways to optimize it (even an inflexible solution is welcome). The total boot time from power-on to loading payload is around 20 seconds with logs disabled.