Convert mpc7448hpc2 to CONFIG_OF_LIBFDT

This was configured to use the deprecated CONFIG_OF_FLAT_TREE, change
to CONFIG_OF_LIBFDT.

WARNING: This conversion is untested because I do not have a board to
test it on.

NOTE: The FDT blob (DTS) must have an /aliases/ethernet0 and (optionally)
/aliases/ethernet1 property for the ethernet to work.

Signed-off-by: Gerald Van Baren <vanbaren@cideas.com>
diff --git a/include/configs/mpc7448hpc2.h b/include/configs/mpc7448hpc2.h
index a218f75..3d71e22 100644
--- a/include/configs/mpc7448hpc2.h
+++ b/include/configs/mpc7448hpc2.h
@@ -75,7 +75,7 @@
 #define CFG_PROMPT_HUSH_PS2	"> "
 
 /* Pass open firmware flat tree */
-#define CONFIG_OF_FLAT_TREE	1
+#define CONFIG_OF_LIBFDT	1
 #define CONFIG_OF_BOARD_SETUP	1
 
 #define OF_CPU			"PowerPC,7448@0"