Blackfin: enable 64bit printf for nand

Since the NAND code now uses 64bit code, make sure we enable support for
ADI Blackfin boards in printf to avoid the warning:
nand_util.c:45:2: warning: #warning Please define CONFIG_SYS_64BIT_VSPRINTF for correct output!

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

include/configs/bfin_adi_common.h

@@ -87,6 +87,9 @@
 #  define CONFIG_CMD_SPIBOOTLDR
 # endif
 #endif
+#ifdef CONFIG_CMD_NAND
+# define CONFIG_SYS_64BIT_VSPRINTF
+#endif
 
 /*
  * Console Settings