[SCSI] fcoe: Remove redundant 'less than zero' check

strtoul returns an 'unsigned long' so there is no
reason to check if the value is less than zero.

strtoul already checks for the '-' character deep
in its bowels. It will return an error if the user
has provided a negative value and fcoe_str_to_dev_loss
will return that error to its caller.

This patch fixes the following Coverity reported warning:

CID 703581 -  NO_EFFECT Unsigned compared against 0 - This
less-than-zero comparison of an unsigned value is never true. "*val < 0UL".
drivers/scsi/fcoe/fcoe_sysfs.c:105
Signed-off-by: NRobert Love <robert.w.love@intel.com>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

drivers/scsi/fcoe/fcoe_sysfs.c

@@ -102,7 +102,7 @@ static int fcoe_str_to_dev_loss(const char *buf, unsigned long *val)
 	int ret;
 
 	ret = kstrtoul(buf, 0, val);
-	if (ret || *val < 0)
+	if (ret)
 		return -EINVAL;
 	/*
 	 * Check for overflow; dev_loss_tmo is u32