scan/ellsi: set recv timeout to 5 seconds unconditionally

This is so we can reliably detect disconnect even in cases such as an
unplugged network cable: the server sends a heartbeat every 2.5 seconds. If
we fail to read anything after 5 seconds we can safely assume the server is
dead or unreachable.

MultiCAN/src/drivers/scan/ellsi.c

@@ -434,7 +434,7 @@ static int ellsi_connect(void *pvt) {
         fprintf(stderr, "ellsi_connect: error in socket connect (%s)\n", ERRNO_STR(buf));
         return -1;
     }
-    /* set recv timout for during connect */
+    /* set recv timout to 5 seconds so we can detect missing heartbeat (every 2.5 seconds) */
     if (setsockopt(state->sock, SOL_SOCKET, SO_RCVTIMEO, &tmo, sizeof(tmo)) < 0) {
         fprintf(stderr, "ellsi_connect: error setting socket option SO_RCVTIMEO (%s)\n",
             ERRNO_STR(buf));
@@ -452,13 +452,6 @@ static int ellsi_connect(void *pvt) {
     if (ellsi_add_can_ids(state)) {
         return -1;
     }
-    /* reset timout for recv operation to zero (default, infinite) */
-    tmo.tv_sec = 0;
-    if (setsockopt(state->sock, SOL_SOCKET, SO_RCVTIMEO, &tmo, sizeof(tmo)) < 0) {
-        fprintf(stderr, "ellsi_connect: error resetting socket option SO_RCVTIMEO (%s)\n",
-            ERRNO_STR(buf));
-        return -1;
-    }
     return 0;
 }