[new uImage] Pull in libfdt if CONFIG_FIT is enabled

New uImage format (Flattened Image Tree) requires libfdt
functionality, print out error message if CONFIG_OF_LIBFDT
is not defined.

New uImage support is enabled by defining CONFIG_FIT (and CONFIG_OF_LIBFDT).
This commit turns it on by default.

Signed-off-by: Marian Balakowicz <m8@semihalf.com>
diff --git a/cpu/mpc5xxx/cpu.c b/cpu/mpc5xxx/cpu.c
index e4d6168..7522afe 100644
--- a/cpu/mpc5xxx/cpu.c
+++ b/cpu/mpc5xxx/cpu.c
@@ -114,7 +114,7 @@
 
 /* ------------------------------------------------------------------------- */
 
-#ifdef CONFIG_OF_LIBFDT
+#if defined(CONFIG_OF_LIBFDT) && defined (CONFIG_OF_BOARD_SETUP)
 void ft_cpu_setup(void *blob, bd_t *bd)
 {
 	int div = in_8((void*)CFG_MBAR + 0x204) & 0x0020 ? 8 : 4;