main/postmarketos-mkinitfs: Center splash images on the screen (MR 2662)

Alpine patches busybox to support image alignment in [1].
So far we don't need to align the spalshes in postmarketOS as those are
generated per device. However with generic images it becomes impossible
to support multiple resolutions with this approach.
Set the alignment to "Center" in fbsplash config so generic system
images can reuse the splash on multiple resolutions.

[1] - https://gitlab.alpinelinux.org/alpine/aports/-/blob/master/main/busybox/0008-fbsplash-support-image-and-bar-alignment-and-positio.patch

[ci:skip-build] already built successfully in CI

main/postmarketos-mkinitfs/APKBUILD

@@ -2,7 +2,7 @@
 # Co-Maintainer: Clayton Craft <clayton@craftyguy.net>
 pkgname=postmarketos-mkinitfs
 pkgver=1.1.2
-pkgrel=1
+pkgrel=2
 pkgdesc="Tool to generate initramfs images for postmarketOS"
 url="https://postmarketos.org"
 depends="
@@ -69,5 +69,5 @@ sha512sums="
 67341444c21fc884751ee12fec4069132184d6346fe6dee3f90989ed1417322336c3f135a5099dce5cecce64ad1f2a5e7ce254e5fdc772e20a150facb09f3763  postmarketos-mkinitfs-1.1.2.tar.gz
 950ac042f19055979cb53b39be93866c88aba0acd5a49cd768522505991e2bd2851735677e777caa6c8973e006318582ddd975214eccc5c35c2c1d649af6d71e  00-default.modules
 40033b421e79999c85bd72e1353fe6745a87fcbf9f6a5b8180e832c7f340da7d4e33d056f557ae95a9924f5d186a6e728f3ed53c0922cdac4c39513fdc3e3a82  init.sh
-8c411d808a0830344d447f2c8afdcd98b40b493ae982638e66e7e095a9d3fd1024d4034762631d9f7c0667d1553e5a40f9847b8cbb48c2a09e6a6d49c3ad6d7d  init_functions.sh
+ac097c23ea8807aeac9af6ee1ced4fb41f2e108d9ebed61062decec02a2f0cece8bf1d5f45e5d52928ccead09f0b44190f6b1008018b6d845ba1b5d26679d82f  init_functions.sh
 "

main/postmarketos-mkinitfs/init_functions.sh

@@ -588,8 +588,9 @@ show_splash() {
 		return
 	fi
 
+	echo "IMG_ALIGN=CM" >>/tmp/fbsplash.cfg
 	gzip -c -d "$1" >/tmp/splash.ppm
-	fbsplash -s /tmp/splash.ppm
+	fbsplash -s /tmp/splash.ppm -i /tmp/fbsplash.cfg
 }
 
 show_splash_loading() {