notifier: modify the oid schema for SNMP notification.

MIB syntax tested using:
$ smilint -p packaging/doc/mibs/REDHAT-MIB.txt -l 6 \
          packaging/doc/mibs/OVIRT-MIB.txt

Change-Id: Ic8a06063f8ebbbe4d05783cb25036e870a6be3b7
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1136818
Signed-off-by: Mooli Tayer <mtayer@redhat.com>