lightmediascanner: remove udev workaround

lightmediascanner: remove udev workaround

Now that DBUS events on monitored mounted directories works
the workaround can be removed.

Change-Id: Ia4ac369a47aefc33f0aa9276a31841d0a64cd2da
Bug-AGL: SPEC-628
Signed-off-by: Matt Ranostay <matt.ranostay@konsulko.com>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/9533
Tested-by: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
ci-image-build: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
Reviewed-by: Scott Murray <scott.murray@konsulko.com>
Reviewed-by: Stéphane Desneux <stephane.desneux@iot.bzh>
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>