TI DaVinci: DM355 Leopard: Fix compilation warning

We get a compliation warning when we enable the NAND driver
for DM355 leopard. The waring we get is that we have
an implicit declaration of davinci_nand_init.

It is fixed by including the asm/arch/nand_defs.h header file

Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>

board/davinci/dm355leopard/dm355leopard.c

@@ -21,6 +21,7 @@
 #include <asm/io.h>
 #include <asm/arch/hardware.h>
 #include <asm/arch/gpio_defs.h>
+#include <asm/arch/nand_defs.h>
 #include "../common/misc.h"
 #include <net.h>
 #include <netdev.h>