Add a last-ditch effort check for PS1 EBOOTs.

If this doesn't work either, I don't know what else will, as PS1 EBOOTs are *supposed* to have PSISOIMG0000 in their file somewhere, and use the PARAM SFO category "ME".

I can only assume bsauvage's ps1 eboot is improperly made somehow, but if it doesn't contain ME in the PARAM SFO, I think we're screwed anyway.