Corrected MGS3 comment, because OCD also new CRC

There is no such thing as MGS3 Substance only Subsistence. Substance is MGS2 :P
Also this new CRC is US Disc 2 of Subsistence. The blue stripes should be fixed now I guess.
Update GSCrc.cpp
Merge pull request #62 from Blackbird88/patch-1

Corrected MGS3 comment, because OCD also new CRC