Revert "Use our git"

This reverts commit 57840eab683583e89ba506800c08ee752937c586.

We're shutting down git.archlinux.org and don't want to move the linux
repo to gitlab due to its size.

PKGBUILD

@@ -5,7 +5,7 @@ pkgver=5.12.13.arch1
 pkgrel=1
 pkgdesc='Linux'
 _srctag=v${pkgver%.*}-${pkgver##*.}
-url="https://git.archlinux.org/linux.git/log/?h=$_srctag"
+url="https://github.com/archlinux/linux/commits/$_srctag"
 arch=(x86_64)
 license=(GPL2)
 makedepends=(
@@ -16,7 +16,7 @@ makedepends=(
 options=('!strip')
 _srcname=archlinux-linux
 source=(
-  "$_srcname::git+https://git.archlinux.org/linux.git?signed#tag=$_srctag"
+  "$_srcname::git+https://github.com/archlinux/linux?signed#tag=$_srctag"
   config         # the main kernel config file
 )
 validpgpkeys=(