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/configs/openrd_client_defconfig b/configs/openrd_client_defconfig
new file mode 100644
index 0000000..c342315
--- /dev/null
+++ b/configs/openrd_client_defconfig
@@ -0,0 +1,7 @@
+CONFIG_ARM=y
+CONFIG_KIRKWOOD=y
+CONFIG_TARGET_OPENRD=y
+CONFIG_SYS_EXTRA_OPTIONS="BOARD_IS_OPENRD_CLIENT"
+# CONFIG_CMD_IMLS is not set
+# CONFIG_CMD_FLASH is not set
+# CONFIG_CMD_SETEXPR is not set