base,cpu,dev: Simplify ListenSocket::listen().

Remove the "reuse" parameter which default to true and was always
also explicitly set to true. Tidy up the code itself slightly, mostly
by using "panic_if" to remove some nesting.

Change-Id: Ie23971aabf2fe4252d27f1887468360722a72379
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/69159
Maintainer: Gabe Black <gabeblack@google.com>
Reviewed-by: Yu-hsin Wang <yuhsingw@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/base/socket.hh

@@ -106,7 +106,7 @@ class ListenSocket
 
     virtual int accept();
 
-    virtual bool listen(int port, bool reuse = true);
+    virtual bool listen(int port);
 
     int getfd() const { return fd; }
     bool islistening() const { return listening; }