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/arch/arm/mach-kirkwood/Kconfig b/arch/arm/mach-kirkwood/Kconfig
index aab5d19..f7737bf 100644
--- a/arch/arm/mach-kirkwood/Kconfig
+++ b/arch/arm/mach-kirkwood/Kconfig
@@ -4,6 +4,9 @@
 	prompt "Marvell Kirkwood board select"
 	optional
 
+config TARGET_OPENRD
+	bool "Marvell OpenRD Board"
+
 config TARGET_DREAMPLUG
 	bool "DreamPlug Board"
 
@@ -51,6 +54,7 @@
 config SYS_SOC
 	default "kirkwood"
 
+source "board/Marvell/openrd/Kconfig"
 source "board/Marvell/dreamplug/Kconfig"
 source "board/Marvell/guruplug/Kconfig"
 source "board/Marvell/sheevaplug/Kconfig"