device-htc-m8: specify 'system' as rootfs partition (MR 4799)

On HTC devices with S-On still active, the 'userdata' partition
is not writable. Change the default rootfs partition to the
'system' partition, which is writable.

device/testing/device-htc-m8/APKBUILD

@@ -2,7 +2,7 @@
 pkgname=device-htc-m8
 pkgdesc="HTC One M8"
 pkgver=0.1
-pkgrel=16
+pkgrel=17
 url="https://postmarketos.org"
 license="MIT"
 arch="armv7"
@@ -31,7 +31,7 @@ nonfree_firmware() {
 }
 
 sha512sums="
-31665a740ef686d6b371c14eb9d13c706b94c3c961158dcfba6a8a572602b49fba4d569003e323380374bb7954fd757cc155bda1aa34e93011d6ed103809e8bf  deviceinfo
+a516a758dad4204e226f1d628d19ac5d9f9fe0138970ba0995cb25b94746caa1f9f530a81d8befdc914680bafaed34675c895ce09329d0cfb292bf1be49a5dda  deviceinfo
 765abaad5fda0dfda5e62e1e48414d3eea822198f39d0792171a04d73f86f6273a6e562afab430cbfcdd084412568a0ad03d012e9c40c5564f5cd1b9c0f181eb  initfs-hook.sh
 f0f69ab3b5b3fed11ec5049f37c71c4e9dcf87dc1f238199a3917dd61957d46783a8798d63d400cc5d3983987e750e3fec6d7117561ad5005f28131ae4821d66  90-android-touch-dev.rules
 "

device/testing/device-htc-m8/deviceinfo

@@ -17,6 +17,7 @@ deviceinfo_screen_height="1920"
 
 # Bootloader related
 deviceinfo_flash_method="fastboot"
+deviceinfo_flash_fastboot_partition_rootfs="system"
 deviceinfo_kernel_cmdline="console=ttyHSL0,115200,n8 androidboot.hardware=qcom user_debug=31 ehci-hcd.park=3 zcache androidboot.selinux=permissive"
 deviceinfo_generate_bootimg="true"
 deviceinfo_bootimg_qcdt="true"