main/postmarketos-base-downstream: add disable-udev-v4l subpackage (MR 4768)

Which replaces /lib/udev/rules.d/60-persistent-v4l.rules (from the
eudev package) with a symlink to /dev/null.  Around 20 devices need
this to fix a kernel panic with downstream kernel when starting udev.
Issue happens due to that camera firmware is missing and/or not loaded
properly.

main/postmarketos-base-downstream/APKBUILD

 # Maintainer: Henrik Grimler <henrik@grimler.se>
 pkgname=postmarketos-base-downstream
-pkgver=1
+pkgver=2
 pkgrel=0
 pkgdesc="Base package for devices with downstream (vendor) kernels"
 url="https://postmarketos.org"
 arch="noarch"
 license="GPL-3.0-or-later"
-subpackages="$pkgname-lightdm"
+subpackages="
+	$pkgname-disable-udev-v4l:disable_udev_v4l
+	$pkgname-lightdm
+"
 source="10-logind-check-graphical.conf"
 
 package() {
 	mkdir -p "$pkgdir"
 }
 
+disable_udev_v4l() {
+	# On some devices the kernel panics or hangs when starting
+	# udev if camera firmware is missing and/or fails to load
+	pkgdesc="Package to disable udev video4linux rules"
+	replaces="eudev"
+	mkdir -p "$subpkgdir"/lib/udev/rules.d
+	ln -s /dev/null "$subpkgdir"/lib/udev/rules.d/60-persistent-v4l.rules
+}
+
 lightdm() {
 	install_if="$pkgname=$pkgver-r$pkgrel lightdm"