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/pcm052_defconfig b/configs/pcm052_defconfig
index 49159ce..f97f110 100644
--- a/configs/pcm052_defconfig
+++ b/configs/pcm052_defconfig
@@ -11,3 +11,4 @@
 CONFIG_NAND_VF610_NFC=y
 CONFIG_SYS_NAND_BUSWIDTH_16BIT=y
 CONFIG_FSL_LPUART=y
+CONFIG_OF_LIBFDT=y