make isofs `system.cnf` parser accept `cdrom1:\\`

[israpps]

Pull Request checklist

Note: these are not necessarily requirements

• [ ] I reformatted the code with clang-format
• [ ] I checked to make sure my submission worked
• [x] I am the author of submission or have permission from the original author
• [ ] Requires update of the PS2SDK
• [ ] Requires update of the gsKit
• [ ] Others (please specify below)

Pull Request description

Some crappy game mods use cdrom1:\\ instead, not sure why, but a considerable ammount of silly users don't like seing their game mods marked as invalid and they switch back to winhiip