Small fix

wrappers/mtproto_intermediate.go

 		"counter", m.writeCounter,
 	)
 
-	if m.opts.ReadHacks.SimpleAck {
+	if m.opts.WriteHacks.SimpleAck {
 		return m.conn.Write(p)
 	}
 

wrappers/mtproto_intermediate_secure.go

 		"counter", m.writeCounter,
 	)
 
-	if m.opts.ReadHacks.SimpleAck {
+	if m.opts.WriteHacks.SimpleAck {
 		return m.conn.Write(p)
 	}