arm: kirkwood: Enable uart0 dm-pre-reloc for Pogoplug V4 board

When DM_SERIAL is enabled, the device-tree tag u-boot,dm-pre-reloc is
required for this board to boot over UART with kwboot. Enable this in
kirkwood-pogoplug-series-4-u-boot.dtsi.

Added by Stefan while applying:
Please note that it's not fully understood, why this property really
is needed. Here a link to the discussion about this:

https://lore.kernel.org/r/20230201080210.ypz4nrj4y2igwxz3@pali/

Signed-off-by: Tony Dinh <mibodhi@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>

diff --git a/arch/arm/dts/kirkwood-pogoplug-series-4-u-boot.dtsi b/arch/arm/dts/kirkwood-pogoplug-series-4-u-boot.dtsi
new file mode 100644 (file)
index 0000000..f9e1272
--- /dev/null
+++ b/arch/arm/dts/kirkwood-pogoplug-series-4-u-boot.dtsi
@@ -0,0 +1,7 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2023 Tony Dinh <mibodhi@gmail.com>
+ */
+&uart0 {
+       u-boot,dm-pre-reloc;
+};