Kernel: Merge do_retransmit_packets() into retransmit_packets()

Author: https://github.com/gunnarbeutner
Commit: c22296505c
Pull-request: https://github.com/SerenityOS/serenity/pull/7078
Reviewed-by: https://github.com/awesomekling

Kernel/Net/TCPSocket.h

@@ -176,7 +176,6 @@ private:
     virtual KResult protocol_bind() override;
     virtual KResult protocol_listen() override;
 
-    void do_retransmit_packets();
     void enqueue_for_retransmit();
     void dequeue_for_retransmit();