arm: Sheevaplug: Fixed NAND specific warning

It is recommended to define the macro CONFIG_SYS_64BIT_VSPRINTF
for NAND specific warning removal, same is done in this patch

Signed-off-by: Prafulla Wadaskar <prafulla@marvell.com>

include/configs/sheevaplug.h

@@ -107,6 +107,7 @@
 #define NAND_MAX_CHIPS			1
 #define CONFIG_SYS_NAND_BASE		0xD8000000	/* KW_DEFADR_NANDF */
 #define NAND_ALLOW_ERASE_ALL		1
+#define CONFIG_SYS_64BIT_VSPRINTF	/* needed for nand_util.c */
 #endif
 
 /*