First convert the motherboard to IT mode from IR mode:

c:>raid\ittool\ph7\smc2008

Then navigate to
92118i folder and run:

sas2flash -o -f 2118it.bin -b mptsas2.rom

http://www.servethehome.com/howto-flash-supermicro-x8si6f-lsi-sas-2008-controller-lsi-firmware/