scripts: fix mountinfo parsing in systemd-autofs-restart.sh

Fily system type is not necessarily located in the column number 9.
But look like we can rely on " - " pattern: it's always located immediately
after dash.

Signed-off-by: Stanislav Kinsburskiy <skinsbursky@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>