core: VdsUpdateRunTimeInfo - update device logical name

This patch adds support to update disks logical names as retrieved from
vdsm.

Change-Id: I08b13ba18ded824d7c62f72766fa7055da6ec49c
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1063597
Signed-off-by: Liron Aravot <laravot@redhat.com>