Linux, Main, Bootloader

- Updated to Kernel 5.15.1. Probably will stay on this kernel (or at least 5.15.x) for some time. It seems USB host driver is more stable, so using default one (instead of downgraded).
- Some fixes and tweaks since last linux release.
-Change reset type to "cold reset" while loading core from USB blaster or LXDE. So make sure bootloader is updated. (Official updater will take care of that).
- Don't load cheat files for non-game files (fixes NES loosing cheats)
- SNES: only skip 512 byte ROM header (srg320)
- TGFX16: fixes in CD (srg320)
- input: fix mouse wheel data transfer.
- input: fix key_menu_as_rgui option.
- UART: save modem baud rate, enable 115200 speed for modem mode.
- Some other fixes and tweaks i've forgot.