samsung-kiran: new device (Samsung Z1)

As far as I know, this is the first attempt to port any alternative OS than Tizen on this device, I am also asking additional help to make this port actually working. Currently this port uses Samsung's downstream kernel for SC7727S.

Remaining issues:

• Boot image generation:
  • dtbtool-sprd should work, but the fork in Tizen supports Qualcomm and Samsung SoCs. Tizen version of dtbtool-sprd is not uploaded yet to any public git repos, and I'd suggest to create an apk for this.
  • The bootloader expects dzImage, which is again used only in Tizen and not uploaded elsewhere yet. Also I'd suggest to create an apk for this.
• Display: The sprdfb framebuffer driver of this phone is... different from other Android phones with this chipset. It implements a DRM(!) driver, which does not support modesetting, so the framebuffer is broken. Tizen on this device uses Xorg and custom display driver which seems to handle modesetting and some other procedures, although that driver itself is proprietary. What would be the best choice to make display working?
• Wi-Fi of this device uses Broadcom BCM4343S. I have extracted the firmware from Tizen, didn't uploaded it yet to any public git repos yet.
• GPS: Broadcom BCM47520, seems to use proprietary binary in Tizen to activate this.
• Audio, cellular, sensors: not tested yet, as GUI is not working.
• Touchscreen and hardware keys are working, tested with evtest.

device/testing/device-samsung-kiran/APKBUILD

+# Reference: <https://postmarketos.org/devicepkg>
+pkgname=device-samsung-kiran
+pkgdesc="Samsung Z1"
+pkgver=0.1
+pkgrel=0
+url="https://postmarketos.org"
+license="MIT"
+arch="armv7"
+options="!check !archcheck"
+depends="
+	linux-samsung-kiran
+	mesa-dri-gallium
+	postmarketos-base
+	alsa-utils
+	alsa-ucm-conf
+	soc-sprd-audio-sc8830
+"
+makedepends="devicepkg-dev"
+install="$pkgname.post-install"
+subpackages="$pkgname-nonfree-firmware:nonfree_firmware"
+source="deviceinfo"
+
+build() {
+	devicepkg_build $startdir $pkgname
+}
+
+package() {
+	devicepkg_package $startdir $pkgname
+}
+
+nonfree_firmware() {
+	pkgdesc="Firmware for Wi-Fi"
+	depends="firmware-samsung-kiran"
+	mkdir "$subpkgdir"
+}
+
+sha512sums="
+0df41c94df913a4280cda14bba98e2b343f422152691924d883afac8c8e73e1958df19e2d218130cd26ab952cda5e17bed7f488fca0c2fe0909728bd5dfbd9dd  deviceinfo
+"