[MM-16751] golint model (#17896)

model/post_embed.go

@@ -4,10 +4,10 @@
 package model
 
 const (
-	POST_EMBED_IMAGE              PostEmbedType = "image"
-	POST_EMBED_MESSAGE_ATTACHMENT PostEmbedType = "message_attachment"
-	POST_EMBED_OPENGRAPH          PostEmbedType = "opengraph"
-	POST_EMBED_LINK               PostEmbedType = "link"
+	PostEmbedImage             PostEmbedType = "image"
+	PostEmbedMessageAttachment PostEmbedType = "message_attachment"
+	PostEmbedOpengraph         PostEmbedType = "opengraph"
+	PostEmbedLink              PostEmbedType = "link"
 )
 
 type PostEmbedType string