core: allow putting host on maintenance if lonley in dc also for SPM host

fixup to commit 998c17 which introduced this ability but didn't cleanup
irsBrokerCommand cached mCurrentVdsId value, which leaded to keep requesting
for SPMStatus from unreachable or deleted host.

Change-Id: Ib0dc1bb6e4318fc1465b51652d519574a3af4f99
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1055455
Signed-off-by: Yaniv Bronhaim <ybronhei@redhat.com>