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/P1010RDB-PA_NAND_SECBOOT_defconfig b/configs/P1010RDB-PA_NAND_SECBOOT_defconfig
index 201ef61..430284f 100644
--- a/configs/P1010RDB-PA_NAND_SECBOOT_defconfig
+++ b/configs/P1010RDB-PA_NAND_SECBOOT_defconfig
@@ -10,3 +10,4 @@
 CONFIG_E1000=y
 CONFIG_SYS_NS16550=y
 CONFIG_FSL_ESPI=y
+CONFIG_OF_LIBFDT=y