drm/edid: sunset drm_find_cea_extension()

Convert drm_find_cea_extension() to a predicate function to check if the
EDID has a CTA extension or a DisplayID CTA data block. This is mainly
to avoid adding new users that only find the first CTA extension.

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/a5bf228942e6bd0fc70d5cf7a14c249a14a7afcd.1651569697.git.jani.nikula@intel.com

drivers/gpu/drm/drm_edid.c

@@ -3558,30 +3558,29 @@ const u8 *drm_find_edid_extension(const struct edid *edid,
 	return edid_ext;
 }
 
-static const u8 *drm_find_cea_extension(const struct edid *edid)
+/* Return true if the EDID has a CTA extension or a DisplayID CTA data block */
+static bool drm_edid_has_cta_extension(const struct edid *edid)
 {
 	const struct displayid_block *block;
 	struct displayid_iter iter;
-	const u8 *cea;
 	int ext_index = 0;
+	bool found = false;
 
 	/* Look for a top level CEA extension block */
-	/* FIXME: make callers iterate through multiple CEA ext blocks? */
-	cea = drm_find_edid_extension(edid, CEA_EXT, &ext_index);
-	if (cea)
-		return cea;
+	if (drm_find_edid_extension(edid, CEA_EXT, &ext_index))
+		return true;
 
 	/* CEA blocks can also be found embedded in a DisplayID block */
 	displayid_iter_edid_begin(edid, &iter);
 	displayid_iter_for_each(block, &iter) {
 		if (block->tag == DATA_BLOCK_CTA) {
-			cea = (const u8 *)block;
+			found = true;
 			break;
 		}
 	}
 	displayid_iter_end(&iter);
 
-	return cea;
+	return found;
 }
 
 static __always_inline const struct drm_display_mode *cea_mode_for_vic(u8 vic)
@@ -3854,8 +3853,8 @@ add_alternate_cea_modes(struct drm_connector *connector, const struct edid *edid
 	LIST_HEAD(list);
 	int modes = 0;
 
-	/* Don't add CEA modes if the CEA extension block is missing */
-	if (!drm_find_cea_extension(edid))
+	/* Don't add CTA modes if the CTA extension block is missing */
+	if (!drm_edid_has_cta_extension(edid))
 		return 0;
 
 	/*