device-asus-zenfone3: force mdp5 to fix backlight enablement issue

Unlike mdp5, which enables its timing engine immediately, dpu1 defers
timing engine enablement. As a result, the DSI backlight enablement
command is ignored by (or not sent to) the panel until the dpu1 timing
engine is enabled.

Enabling the backlight manually via sysfs after the timing engine has
been enabled works around the issue. However, requiring users to do this
manually would be inconvenient, so force the use of mdp5 instead.

Signed-off-by: Antony Kurniawan Soemardi <postmarketos@smankusors.com>
Part-of: <https://gitlab.postmarketos.org/postmarketOS/pmaports/-/merge_requests/9353>

device/testing/device-asus-zenfone3/APKBUILD

@@ -1,7 +1,7 @@
 maintainer="Antony Kurniawan S. <postmarketos@smankusors.com>"
 pkgname=device-asus-zenfone3
 pkgdesc="Asus Zenfone 3"
-pkgver=4
+pkgver=5
 pkgrel=0
 url="https://postmarketos.org"
 license="MIT"
@@ -24,6 +24,7 @@ subpackages="
 "
 source="
 	deviceinfo
+	kernel-cmdline.conf
 	modules-initfs
 "
 
@@ -49,5 +50,6 @@ kernel_ze552kl() {
 
 sha512sums="
 2e6e5d61fe513550b4c4bb70b7009a23269d6a457e05079d6f4f508bc5944c3c6d0c6160e65795f3a756ff7759cb56fbfdfe5d77f0dabd32ad4914d587c80f93  deviceinfo
+b25878846d45b6394b753fcd9c3fdff9f27d707e3d37662b2f3c5c85de95126de85fe2e5762c0dd0a2680701ab9901aefc743b4922350cfd415cf8c5145b2c82  kernel-cmdline.conf
 a4c56173941e88434073d9980a687a82956fbcaaaf15068fd2b4fd9351011a934c82f67e62ce87440876d673784938cfdaedc70ae03e1943c95baef6205567b1  modules-initfs
 "

device/testing/device-asus-zenfone3/kernel-cmdline.conf

@@ -0,0 +1,2 @@
+# the DSI backlight enablement is not handled properly when using dpu1 engine
+msm.prefer_mdp5=true