Revert "[BACKPORT] net/can: remove psock reference from can connect"

This reverts commit 9ce3fab.

PR reference: apache/nuttx#5467

In order for this commit to be valid, the following other PRs must also
be back-ported first:
- apache/nuttx#5434

Additional PRs that fix related bugs:
- apache/nuttx#5462
- apache/nuttx#5466

net/can/can.h

@@ -117,6 +117,10 @@ struct can_conn_s
   int32_t tx_deadline;
 # endif
 #endif
+
+#ifdef CONFIG_NET_TIMESTAMP
+  FAR struct socket *psock; /* Needed to get SO_TIMESTAMP value */
+#endif
 };
 
 /****************************************************************************

net/can/can_sockif.c

@@ -221,6 +221,12 @@ static int can_setup(FAR struct socket *psock, int protocol)
           return -ENOMEM;
         }
 
+#ifdef CONFIG_NET_TIMESTAMP
+      /* Store psock in conn se we can read the SO_TIMESTAMP value */
+
+      conn->psock = psock;
+#endif
+
       /* Initialize the connection instance */
 
       conn->protocol = (uint8_t)protocol;