Fix uninitialized GPU determinism mode for NAND titles or whatever.

m_strGPUDeterminismMode can be set by either the global or game
settings.  Either way, it's then supposed to be parsed into an enum,
m_GPUDeterminismMode.  However, the code to do this was placed right
after checking for game settings, which doesn't happen at all if there
isn't a valid title ID.  Move it outside the if block.

Thanks to flacs for forwarding a valgrind report, which I think is caused by this.