render/vulkan: make vulkan_format_props_find_modifier() return value const

include/render/vulkan.h

@@ -108,7 +108,7 @@ struct wlr_vk_format_props {
 
 void vulkan_format_props_query(struct wlr_vk_device *dev,
 	const struct wlr_vk_format *format);
-struct wlr_vk_format_modifier_props *vulkan_format_props_find_modifier(
+const struct wlr_vk_format_modifier_props *vulkan_format_props_find_modifier(
 	struct wlr_vk_format_props *props, uint64_t mod, bool render);
 void vulkan_format_props_finish(struct wlr_vk_format_props *props);
 

render/vulkan/pixel_format.c

@@ -414,7 +414,7 @@ void vulkan_format_props_finish(struct wlr_vk_format_props *props) {
 	free(props->render_mods);
 }
 
-struct wlr_vk_format_modifier_props *vulkan_format_props_find_modifier(
+const struct wlr_vk_format_modifier_props *vulkan_format_props_find_modifier(
 		struct wlr_vk_format_props *props, uint64_t mod, bool render) {
 	if (render) {
 		for (unsigned i = 0u; i < props->render_mod_count; ++i) {

render/vulkan/texture.c

@@ -451,7 +451,7 @@ VkImage vulkan_import_dmabuf(struct wlr_vk_renderer *renderer,
 
 	uint32_t plane_count = attribs->n_planes;
 	assert(plane_count < WLR_DMABUF_MAX_PLANES);
-	struct wlr_vk_format_modifier_props *mod =
+	const struct wlr_vk_format_modifier_props *mod =
 		vulkan_format_props_find_modifier(fmt, attribs->modifier, for_render);
 	if (!mod) {
 		wlr_log(WLR_ERROR, "Format %"PRIx32" (%.4s) can't be used with modifier "