linux-dmabuf-v1: fix MOD_INVALID handling in feedback tranches

[1] has changed wlr_drm_format to remove the assumption that
MOD_INVALID is always implicitly enabled. MOD_INVALID is now part
of the modifier list just like any other modifier.

The patch adding support for linux-dmabuf-v1 feedback has been
written a lot of time before [1], and hasn't been updated accordingly
when merged. This results in MOD_INVALID being advertised twice [2] and
other index bugs.

Fix these issues by removing special-casing for MOD_INVALID.

[1]: https://gitlab.freedesktop.org/wlroots/wlroots/-/merge_requests/3231
[2]: https://github.com/swaywm/sway/issues/7028

types/wlr_linux_dmabuf_v1.c

@@ -475,16 +475,12 @@ static ssize_t get_drm_format_set_index(const struct wlr_drm_format_set *set,
 			format_found = true;
 			break;
 		}
-		idx += 1 + fmt->len;
+		idx += fmt->len;
 	}
 	if (!format_found) {
 		return -1;
 	}
 
-	if (modifier == DRM_FORMAT_MOD_INVALID) {
-		return idx;
-	}
-
 	for (size_t i = 0; i < fmt->len; i++) {
 		if (fmt->modifiers[i] == modifier) {
 			return idx;
@@ -506,7 +502,7 @@ static struct wlr_linux_dmabuf_feedback_v1_compiled *feedback_compile(
 	size_t table_len = 0;
 	for (size_t i = 0; i < fallback_tranche->formats->len; i++) {
 		const struct wlr_drm_format *fmt = fallback_tranche->formats->formats[i];
-		table_len += 1 + fmt->len;
+		table_len += fmt->len;
 	}
 	assert(table_len > 0);
 
@@ -533,12 +529,6 @@ static struct wlr_linux_dmabuf_feedback_v1_compiled *feedback_compile(
 	for (size_t i = 0; i < fallback_tranche->formats->len; i++) {
 		const struct wlr_drm_format *fmt = fallback_tranche->formats->formats[i];
 
-		table[n] = (struct wlr_linux_dmabuf_feedback_v1_table_entry){
-			.format = fmt->format,
-			.modifier = DRM_FORMAT_MOD_INVALID,
-		};
-		n++;
-
 		for (size_t k = 0; k < fmt->len; k++) {
 			table[n] = (struct wlr_linux_dmabuf_feedback_v1_table_entry){
 				.format = fmt->format,
@@ -584,20 +574,6 @@ static struct wlr_linux_dmabuf_feedback_v1_compiled *feedback_compile(
 		uint16_t *indices = compiled_tranche->indices.data;
 		for (size_t j = 0; j < tranche->formats->len; j++) {
 			const struct wlr_drm_format *fmt = tranche->formats->formats[j];
-
-			ssize_t index = get_drm_format_set_index(
-				fallback_tranche->formats, fmt->format,
-				DRM_FORMAT_MOD_INVALID);
-			if (index < 0) {
-				wlr_log(WLR_ERROR, "Format 0x%" PRIX32 " and modifier "
-					"INVALID are in tranche #%zu but are missing "
-					"from the fallback tranche",
-					fmt->format, i);
-				goto error_compiled;
-			}
-			indices[n] = index;
-			n++;
-
 			for (size_t k = 0; k < fmt->len; k++) {
 				ssize_t index = get_drm_format_set_index(
 					fallback_tranche->formats, fmt->format, fmt->modifiers[k]);