code cleanup related to devfd checks

alter all checks for devfd value after device_open to
less than zero insted of equals to -1. device_open will
return values different from -1 in case error happens.

In LUKSv1 device_open should always return -1 in case of
error but this check is safer.

The rest is just formating improvement.

lib/utils_wipe.c

@@ -166,7 +166,7 @@ int crypt_wipe(struct device *device,
 
 	/* coverity[toctou] */
 	devfd = device_open(device, flags);
-	if (devfd == -1) {
+	if (devfd < 0) {
 		free(buffer);
 		return errno ? -errno : -EINVAL;
 	}