media: v4l2-fwnode: Avoid using PTR_ERR(NULL)

PTR_ERR(NULL) yields 0 which is commonly used to denote success. This is
the case here, and PTR_ERR(NULL) is apparently shunned upon. Fix this by
explicitly returning 0 if fwnode == NULL.
Reported-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/v4l2-core/v4l2-fwnode.c

@@ -1095,7 +1095,7 @@ v4l2_fwnode_reference_parse_int_props(struct device *dev,
 		}
 	}
 
-	return PTR_ERR(fwnode) == -ENOENT ? 0 : PTR_ERR(fwnode);
+	return !fwnode || PTR_ERR(fwnode) == -ENOENT ? 0 : PTR_ERR(fwnode);
 
 error:
 	fwnode_handle_put(fwnode);