Include missing headers for fdt_support.h

fdt_support.h is missing declarations for bd_t. Including asm/u-boot.h
pulls in the definition.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
diff --git a/include/fdt_support.h b/include/fdt_support.h
index 2286ea7..3f4bc64 100644
--- a/include/fdt_support.h
+++ b/include/fdt_support.h
@@ -9,6 +9,7 @@
 
 #ifdef CONFIG_OF_LIBFDT
 
+#include <asm/u-boot.h>
 #include <linux/libfdt.h>
 
 u32 fdt_getprop_u32_default_node(const void *fdt, int off, int cell,