udev-extraconf: Add collect flag to mount

Adds extra "--collect" flag to the mount command within
automount_systemd. This is intended to fix an observed deadlock after
rapidly inserting and removing external media. This is because if the
mount command fails, the transient mount will enter a failed state. The
next time the media is inserted, automount_systemd bails because the
first consition finds that the file path for the failed transient mount
still exists. This leaves the external media unmounted and cannot be
mounted until the mount is fixed via systemctl or the device is
rebooted.

Adding "--collect" ensures that the transient mount is cleaned up after
entering a failed state, which ensures that the media can still be
mounted when it's re-inserted.

Signed-off-by: Colin McAllister <colinmca242@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>