Fix Compliation warning for SBC35-A9G20 board

The patch fixes a compilation warning by defining
CONFIG_SYS_64BIT_VSPRINTF in the config file

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

include/configs/sbc35_a9g20.h

@@ -161,6 +161,7 @@
 #define CONFIG_ENV_OFFSET		0x60000
 #define CONFIG_ENV_OFFSET_REDUND	0x80000
 #define CONFIG_ENV_SIZE			0x20000
+#define CONFIG_SYS_64BIT_VSPRINTF	/* needed for nand_util.c */
 #endif
 
 #define CONFIG_BOOTCOMMAND	"nboot 0x21000000 0 400000"