This updates the Linux kernel configuration, removing irrelevant
networking-related components, and switching framebuffer drivers to
the DRM-based ones. With this, we can finally bootstrap on systems
with newer NVIDIA cards, which would green screen with the nvidiafb
driver.
KVM is still disabled, see #443 - VIRTUALIZATION is also disabled,
as it's useless without KVM or any other suboption being enabled.
Additionally, we can now drop the bad-asm patch, since our newer
binutils has no problem supporting that syntax, and it doesn't look
quite innocuous to me, removing an offset from a memory access.
The kernel is now built in 2 stages: first, we build vmlinux only,
then, after cleaning up any intermediate .o files (except the ones
needed to build efistub), we convert it to a bzImage. This required
some creative use of the -o option to convince Make not to rebuild
all of the .o files we've just deleted as dependencies.