Linux: dev_flash location

[Enverex]

A commit a long time ago created the dev_flash data/font folders for Windows setups (#296), but these appear to be missing on the Linux side. ~/.config/rpcs3 is created, but no folder relating to dev_flash is created at any point.

Probably also worth adding to the documentation where dev_flash should actually exist on Linux systems.

[Nekotekina]

TODO list:

1. Delete fs::get_executable_dir
2. Create dev_flash/dev_hdd0/... automatically in config folder

[hcorion]

Can this bug be closed? dev_flash seems to now be auto creating itself.