arm: dts: Enable device-tree overlay support for sun8i-h3 pi devices

Add the '-@' DTC option for the sun8i-h3 pi-class devices. This option
populates the '__symbols__' node that contains all the necessary symbols
for supporting device-tree overlays (for instance from the firmware or
the bootloader) on these devices.

These devices allow various modules to be connected and this enables
users to create out-of-tree device-tree overlays for these modules.

Please note that this change does increase the size of the resulting DTB
by ~30%. For example, with v6.4 increase in size is as follows:

22909 -> 29564 sun8i-h3-orangepi-lite.dtb
24214 -> 30935 sun8i-h3-bananapi-m2-plus.dtb
23915 -> 30664 sun8i-h3-nanopi-m1-plus.dtb
22969 -> 29537 sun8i-h3-nanopi-m1.dtb
24157 -> 30836 sun8i-h3-nanopi-duo2.dtb
24110 -> 30845 sun8i-h3-orangepi-plus2e.dtb
23472 -> 30037 sun8i-h3-orangepi-one.dtb
24600 -> 31410 sun8i-h3-orangepi-plus.dtb
23618 -> 30230 sun8i-h3-orangepi-2.dtb
22170 -> 28548 sun8i-h3-orangepi-zero-plus2.dtb
23258 -> 29795 sun8i-h3-nanopi-neo-air.dtb
23113 -> 29699 sun8i-h3-zeropi.dtb
22803 -> 29270 sun8i-h3-nanopi-neo.dtb
24674 -> 31318 sun8i-h3-nanopi-r1.dtb
23477 -> 30038 sun8i-h3-orangepi-pc.dtb
24622 -> 31380 sun8i-h3-bananapi-m2-plus-v1.2.dtb
23750 -> 30366 sun8i-h3-orangepi-pc-plus.dtb

Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://lore.kernel.org/r/20230627133703.355893-1-felix.moessbauer@siemens.com
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>

Author: fmoessbauer

arch/arm/boot/dts/allwinner/Makefile

@@ -179,6 +179,25 @@ dtb-$(CONFIG_MACH_SUN7I) += \
 	sun7i-a20-pcduino3-nano.dtb \
 	sun7i-a20-wexler-tab7200.dtb \
 	sun7i-a20-wits-pro-a20-dkt.dtb
+
+# Enables support for device-tree overlays for all pis
+DTC_FLAGS_sun8i-h3-orangepi-lite := -@
+DTC_FLAGS_sun8i-h3-bananapi-m2-plus := -@
+DTC_FLAGS_sun8i-h3-nanopi-m1-plus := -@
+DTC_FLAGS_sun8i-h3-nanopi-m1 := -@
+DTC_FLAGS_sun8i-h3-nanopi-duo2 := -@
+DTC_FLAGS_sun8i-h3-orangepi-plus2e := -@
+DTC_FLAGS_sun8i-h3-orangepi-one := -@
+DTC_FLAGS_sun8i-h3-orangepi-plus := -@
+DTC_FLAGS_sun8i-h3-orangepi-2 := -@
+DTC_FLAGS_sun8i-h3-orangepi-zero-plus2 := -@
+DTC_FLAGS_sun8i-h3-nanopi-neo-air := -@
+DTC_FLAGS_sun8i-h3-zeropi := -@
+DTC_FLAGS_sun8i-h3-nanopi-neo := -@
+DTC_FLAGS_sun8i-h3-nanopi-r1 := -@
+DTC_FLAGS_sun8i-h3-orangepi-pc := -@
+DTC_FLAGS_sun8i-h3-bananapi-m2-plus-v1.2 := -@
+DTC_FLAGS_sun8i-h3-orangepi-pc-plus := -@
 dtb-$(CONFIG_MACH_SUN8I) += \
 	sun8i-a23-evb.dtb \
 	sun8i-a23-gt90h-v4.dtb \