[PATCH v2 1/2] configs: Add rock5b_plus-rk3588_defconfig

[Bryan Hinton]

Add a Radxa ROCK 5B+ defconfig that augments the ROCK 5B defconfig
via #include and sets the minimal deltas to select the 5B+ upstream DTS.

Tested on ROCK 5B+ rev 1.2 (32 GB LPDDR5), booting U-Boot from microSD.
Build/test details:
  - U-Boot build string: U-Boot 2026.01-rc1-00243-gd128b673cfb2 (Nov 04 2025 - 13:08:23 -0600)
  - GCC: aarch64-linux-gnu-gcc 15.1.0
  - TPL: rk3588_ddr_lp4_2112MHz_lp5_2400MHz_v1.19.bin
  - BL31: rk3588_bl31_v1.51.elf
  - Verified: control FDT present; `mmc list` shows SD/eMMC; `usb tree` enumerates.

Signed-off-by: Bryan Hinton <bryan at bryanhinton.com>
---
 configs/rock5b_plus-rk3588_defconfig | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 configs/rock5b_plus-rk3588_defconfig

diff --git a/configs/rock5b_plus-rk3588_defconfig b/configs/rock5b_plus-rk3588_defconfig
new file mode 100644
index 00000000000..89cb7fc20b1
--- /dev/null
+++ b/configs/rock5b_plus-rk3588_defconfig
@@ -0,0 +1,5 @@
+#include <configs/rock5b-rk3588_defconfig>
+CONFIG_OF_UPSTREAM=y
+CONFIG_DEFAULT_DEVICE_TREE="rockchip/rk3588-rock-5b-plus"
+CONFIG_OF_LIST="rockchip/rk3588-rock-5b-plus"
+CONFIG_DEFAULT_FDT_FILE="rockchip/rk3588-rock-5b-plus.dtb"
-- 
2.51.2