drm/edid: add drm_edid helper for drm_detect_hdmi_monitor()

We'll need to propagate drm_edid everywhere.

v2: Handle NULL EDID pointer (Ville, CI)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/2fbee0d7b544b44ef0866bb154beefac5d260bec.1652097712.git.jani.nikula@intel.com

drivers/gpu/drm/drm_edid.c

@@ -5113,18 +5113,7 @@ int drm_av_sync_delay(struct drm_connector *connector,
 }
 EXPORT_SYMBOL(drm_av_sync_delay);
 
-/**
- * drm_detect_hdmi_monitor - detect whether monitor is HDMI
- * @edid: monitor EDID information
- *
- * Parse the CEA extension according to CEA-861-B.
- *
- * Drivers that have added the modes parsed from EDID to drm_display_info
- * should use &drm_display_info.is_hdmi instead of calling this function.
- *
- * Return: True if the monitor is HDMI, false if not or unknown.
- */
-bool drm_detect_hdmi_monitor(const struct edid *edid)
+static bool _drm_detect_hdmi_monitor(const struct drm_edid *drm_edid)
 {
 	const struct cea_db *db;
 	struct cea_db_iter iter;
@@ -5134,7 +5123,7 @@ bool drm_detect_hdmi_monitor(const struct edid *edid)
 	 * Because HDMI identifier is in Vendor Specific Block,
 	 * search it from all data blocks of CEA extension.
 	 */
-	cea_db_iter_edid_begin(edid, &iter);
+	cea_db_iter_edid_begin(drm_edid ? drm_edid->edid : NULL, &iter);
 	cea_db_iter_for_each(db, &iter) {
 		if (cea_db_is_hdmi_vsdb(db)) {
 			hdmi = true;
@@ -5145,6 +5134,24 @@ bool drm_detect_hdmi_monitor(const struct edid *edid)
 
 	return hdmi;
 }
+
+/**
+ * drm_detect_hdmi_monitor - detect whether monitor is HDMI
+ * @edid: monitor EDID information
+ *
+ * Parse the CEA extension according to CEA-861-B.
+ *
+ * Drivers that have added the modes parsed from EDID to drm_display_info
+ * should use &drm_display_info.is_hdmi instead of calling this function.
+ *
+ * Return: True if the monitor is HDMI, false if not or unknown.
+ */
+bool drm_detect_hdmi_monitor(const struct edid *edid)
+{
+	struct drm_edid drm_edid;
+
+	return _drm_detect_hdmi_monitor(drm_edid_legacy_init(&drm_edid, edid));
+}
 EXPORT_SYMBOL(drm_detect_hdmi_monitor);
 
 /**