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 fosslinux#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/SHA256SUMS.pkgs

@@ -76,7 +76,7 @@ b39826742e236890f3562cdf19492e7ef4224b271f3e75ddeab1f07982b03ebe  libffi-3.3_0.t
 daae709e98d2df2190d1d13b4e86f7f3fe90fa7a975282fe0bb03289b6539f29  libtool-2.2.4_0.tar.bz2
 6cefa575362149620f8008a32c8af54f0198a18bc6ab910bd3cead196c1507d7  libtool-2.4.7_0.tar.bz2
 503007bbcddcf4e49d26514c59b4c9501f8b42f0c994a59dfdc388b1ae6b7900  libunistring-0.9.10_0.tar.bz2
-05a99e5404bc743570abf514d09a89a719d9443e0e6f196ce92c47a2be774a8a  linux-4.14.336_0.tar.bz2
+72c197889233ad58bd6e73d737fcfed12deac6627347d8b02dcfa215b5ecb9f1  linux-4.14.336_0.tar.bz2
 1d88015de1be5416d4794559962c1c700d72b877cc0ce2a47b28b078d11b2075  linux-headers-4.14.336_0.tar.bz2
 78b0cf6d9312e53c613186cbddd5f747310f375c1f322f33a6ac33682d2f3389  m4-1.4.19_0.tar.bz2
 bd3885a389d3e058081e099850f95aa7938ce1d9b88a187aea6b7196124fbcfe  m4-1.4.7_0.tar.bz2