Revive OpenRD targets

Revert commit 7a2c1b13 which dropped OpenRD boards.
Assume maintainership of OpenRD.
Remove OpenRD from scrapyard.
Switch OpenRD to generic board.
Switch to Thumb build.

Signed-off-by: Albert ARIBAUD <albert.u.boot@aribaud.net>
diff --git a/board/Marvell/openrd/Kconfig b/board/Marvell/openrd/Kconfig
new file mode 100644
index 0000000..124b66d
--- /dev/null
+++ b/board/Marvell/openrd/Kconfig
@@ -0,0 +1,12 @@
+if TARGET_OPENRD
+
+config SYS_BOARD
+	default "openrd"
+
+config SYS_VENDOR
+	default "Marvell"
+
+config SYS_CONFIG_NAME
+	default "openrd"
+
+endif