selftests: mlxsw: rtnetlink: Use devlink_reload() API

The test runs "devlink reload" explicitly. Instead, it is better to use
devlink_reload() which waits for udev events to be processed. Do not sleep
after reload, as devlink_reload() blocks until all the netdevs are renamed.

Signed-off-by: Amit Cohen <[e-mail]>
Reviewed-by: Ido Schimmel <[e-mail]>
Signed-off-by: Petr Machata <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

tools/testing/selftests/drivers/net/mlxsw/rtnetlink.sh

···
 
 	# If we did not handle references correctly, then this should produce a
 	# trace
-	devlink dev reload "$DEVLINK_DEV"
-
-	# Allow netdevices to be re-created following the reload
-	sleep 20
+	devlink_reload
 
 	log_test "bridge vlan flags"
 }
···
 	# devlink reload can be performed without errors
 	RET=0
 
-	devlink dev reload "$DEVLINK_DEV"
-	check_err $? "devlink reload failed"
+	devlink_reload
 
 	log_test "devlink reload - last test"
-
-	sleep 20
 }
 
 trap cleanup EXIT