rockchip: rk3308: Migrate to OF_UPSTREAM

All RK3308 boards has now been synced to Linux kernel v6.8 DTs and can
migrate to use OF_UPSTREAM.

Migrate all RK3308 boards to use OF_UPSTREAM.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/arch/arm/mach-rockchip/Kconfig b/arch/arm/mach-rockchip/Kconfig
index 262cb7c..f1caf4f 100644
--- a/arch/arm/mach-rockchip/Kconfig
+++ b/arch/arm/mach-rockchip/Kconfig
@@ -166,6 +166,7 @@
 	imply LEGACY_IMAGE_FORMAT
 	imply MISC
 	imply MISC_INIT_R
+	imply OF_UPSTREAM
 	imply RNG_ROCKCHIP
 	imply ROCKCHIP_COMMON_BOARD
 	imply ROCKCHIP_OTP