Move CONFIG_OF_LIBFDT to Kconfig

Move this option to Kconfig and tidy up existing boards.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/ls1043aqds_nand_defconfig b/configs/ls1043aqds_nand_defconfig
index 579e247..c27b701 100644
--- a/configs/ls1043aqds_nand_defconfig
+++ b/configs/ls1043aqds_nand_defconfig
@@ -8,3 +8,4 @@
 CONFIG_DM=y
 CONFIG_SPI_FLASH=y
 CONFIG_DM_SPI=y
+CONFIG_OF_LIBFDT=y