Convert CONFIG_SYS_KWD_CONFIG to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_KWD_CONFIG

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/openrd_ultimate_defconfig b/configs/openrd_ultimate_defconfig
index 7c2e41e..ceeb621 100644
--- a/configs/openrd_ultimate_defconfig
+++ b/configs/openrd_ultimate_defconfig
@@ -4,6 +4,7 @@
 CONFIG_ARCH_CPU_INIT=y
 CONFIG_SYS_THUMB_BUILD=y
 CONFIG_ARCH_KIRKWOOD=y
+CONFIG_SYS_KWD_CONFIG="board/Marvell/openrd/kwbimage.cfg"
 CONFIG_SYS_TEXT_BASE=0x600000
 CONFIG_NR_DRAM_BANKS=2
 CONFIG_TARGET_OPENRD=y