render/vulkan/pixel_format: do not leak props->...

`vulkan_format_props_query` calls `query_modifier_support` which
initializes fields of `props` with allocated memory. this memory is
leaked if `query_modifier_support` does not find a supported format
and shmtex is not supported, as in this case `add_fmt_props` ends
up being false and the allocated fields of `props` are never freed.

render/vulkan/pixel_format.c

@@ -296,6 +296,8 @@ void vulkan_format_props_query(struct wlr_vk_device *dev,
 	if (add_fmt_props) {
 		dev->format_props[dev->format_prop_count] = props;
 		++dev->format_prop_count;
+	} else {
+		vulkan_format_props_finish(props);
 	}
 }