Make the Linux kernel & Fiwix->Linux kexec more bare-metal-friendly

[Googulator]

• Enable additional hardware drivers in Linux for better bare metal display, network & input device compatibility
• Disable ATA-over-Ethernet support, because it spams the network with unnecessary packets, is basically useless for bootstrapping, and may even be a security risk
• Increase Fiwix initrd size to 1280MB to fit a larger Linux build
• Make the Fiwix kexec size configurable the same way as initrd (and reduce from 280MB to 256MB which is sufficient in my testing)
• Use a more conservative memory map for Fiwix & Linux
• Boot Linux with consoleblank=0 on bare metal, so the build won't go blind after 5 minutes
• Support kexec-fiwix with interrupts disabled (will be useful later when builder-hex0 is updated)