backend/drm: use pnp.ids to fetch EDID data

backend/drm/gen_pnpids.sh

@@ -0,0 +1,27 @@
+#!/bin/sh -eu
+#
+# usage: gen_pnpids.sh < pnp.ids > pnpids.c
+
+gen_pnps()
+{
+	while read -r id vendor; do
+		[ "${#id}" = 3 ] || exit 1
+
+		printf "\tcase PNP_ID('%c', '%c', '%c'): return \"%s\";\n" \
+			"$id" "${id#?}" "${id#??}" "$vendor"
+	done
+}
+
+cat << EOF
+#include <stdint.h>
+#include <stddef.h>
+#include "backend/drm/util.h"
+#define PNP_ID(a, b, c) ((a & 0x1f) << 10) | ((b & 0x1f) << 5) | (c & 0x1f)
+const char *get_pnp_manufacturer(uint16_t code) {
+	switch (code) {
+$(gen_pnps)
+	}
+	return NULL;
+}
+#undef PNP_ID
+EOF