main/linux-firmware: upgrade to 20200918

use source from upstream tarballs instead of 'git clone' and build
tarball locally and upload it to dev.alpinelinux.org
upstream started to make (about) monthly releases in tarballs from
2019-03-12

remove snapshot(), not needed now
remove not needed variables
clean-up little
7 jobs for !13456 with linux-firmware-20200918 in 5 minutes and 51 seconds
detached
Status Job ID Name Coverage
  Lint
failed #226987
docker-alpine x86_64 allowed to fail
lint

00:00:25

 
  Build
passed #226992
docker-alpine ci-build aarch64
build-aarch64

00:02:54

passed #226993
docker-alpine ci-build armv7
build-armv7

00:03:46

passed #226991
docker-alpine ci-build ppc64le
build-ppc64le

00:04:14

passed #226990
docker-alpine ci-build s390x
build-s390x

00:05:24

passed #226989
docker-alpine ci-build x86
build-x86

00:02:45

passed #226988
docker-alpine ci-build x86_64
build-x86_64

00:02:42

 
Name Stage Failure
failed
lint Lint
No job log