scan: improve error messages in sci_listen

MultiCAN/src/drivers/scan/scan.c

@@ -529,7 +529,8 @@ static void sci_listen(void *parg) {
             memset(&frame, 0, sizeof(frame)); 
             nbytes = port->methods->read(port->driver_pvt, &frame);
             if (nbytes < 0) {
-                errlogSevPrintf(errlogFatal, "sci_listen: read failed (%s)\n", ERRNO_STR(buf));
+                errlogSevPrintf(errlogFatal, "sci_listen: lost connection to CAN port %d\n",
+                    port->port_num);
                 port->connected = 0;
             } else {
 #if 0
@@ -549,7 +550,7 @@ static void sci_listen(void *parg) {
 #endif
                         if (port->methods->write(port->driver_pvt, &parent->frame) < 0) {
                             errlogSevPrintf(errlogFatal,
-                                "sci_listen: automatic rtr response failed on port %d (%s)\n",
+                                "sci_listen: automatic rtr response failed on CAN port %d (%s)\n",
                                 port->port_num, ERRNO_STR(buf));
                         }
                     }
@@ -577,7 +578,7 @@ static void sci_listen(void *parg) {
                 port->connected = (port->methods->connect(port->driver_pvt) == 0);
                 if (port->connected) {
                     errlogSevPrintf(errlogInfo,
-                        "sci_listen: successfully re-connected port %d\n",
+                        "sci_listen: successfully re-connected CAN port %d\n",
                         port->port_num);
                 }
             }