GCC4.6: Squash warning in usb_storage.c

usb_storage.c: In function ‘usb_stor_CB_reset’:
usb_storage.c:466:6: warning: variable ‘result’ set but not used
[-Wunused-but-set-variable]

Signed-off-by: Marek Vasut <marek.vasut@gmail.com>
Cc: Wolfgang Denk <wd@denx.de>
Cc: Simon Glass <sjg@chromium.org>
Cc: Mike Frysinger <vapier@gentoo.org>

common/usb_storage.c

@@ -56,16 +56,17 @@
 #include <part.h>
 #include <usb.h>
 
-#undef USB_STOR_DEBUG
 #undef BBB_COMDAT_TRACE
 #undef BBB_XPORT_TRACE
 
 #ifdef	USB_STOR_DEBUG
-#define USB_STOR_PRINTF(fmt, args...)	printf(fmt , ##args)
+#define USB_BLK_DEBUG	1
 #else
-#define USB_STOR_PRINTF(fmt, args...)
+#define USB_BLK_DEBUG	0
 #endif
 
+#define USB_STOR_PRINTF(fmt, args...)	debug_cond(USB_BLK_DEBUG, fmt, ##args)
+
 #include <scsi.h>
 /* direction table -- this indicates the direction of the data
  * transfer for each command code -- a 1 indicates input