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/tseries_spi_defconfig b/configs/tseries_spi_defconfig
index 901c55e..8244e19 100644
--- a/configs/tseries_spi_defconfig
+++ b/configs/tseries_spi_defconfig
@@ -28,6 +28,7 @@
 CONFIG_SPI_FLASH_STMICRO=y
 # CONFIG_SPI_FLASH_USE_4K_SECTORS is not set
 CONFIG_SYS_NS16550=y
+CONFIG_OF_LIBFDT=y
 CONFIG_USB=y
 CONFIG_USB_MUSB_HOST=y
 CONFIG_USB_STORAGE=y