Update Linux kernel configuration & patches

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.

steps/linux-4.14.336/patches/bad-asm.patch

@@ -1,18 +0,0 @@
-SPDX-FileCopyrightText: 2021 fosslinux <fosslinux@aussies.space>
-
-SPDX-License-Identifier: GPL-2.0-only
-
-Remove the 68() which I'm not really sure what it does but still works and
-breaks our version of binutils.
-
---- arch/x86/boot/bioscall.S	2021-07-31 17:50:09.519480274 +1000
-+++ arch/x86/boot/bioscall.S	2021-07-31 18:21:32.086972277 +1000
-@@ -65,7 +65,7 @@
- 	movw	%ax, %es
- 
- 	/* Copy output state from stack frame */
--	movw	68(%esp), %di	/* Original %cx == 3rd argument */
-+	movw	%sp, %di	/* Original %cx == 3rd argument */
- 	andw	%di, %di
- 	jz	4f
- 	movw	%sp, %si