Pimd : S,G Mroute entries are not expiring even after KAT expiry,

Pimd : S,G Mroute entries are not expiring  even after KAT expiry,
       become stale entries.

Topology:
--------
Source
|
FHR
|
RP ------ LHR --- Recv1
|
Recv2

Root case :
-----------
When RP acts as a LHR i.e RP has a local receiver and registed for
the same group where LHR connected receiver also registered for the
same multicast group.When RP receives a (s,g) join form LHR , it
increments upstream ref count to two to track the Local membership
as well.But at the time of KAT expiry in RP , upstream reference
is not being removed Which is added to track local membership which
is causing to make these entries as stale in RP and FHR.

Fix : Made the change such that it removes the upstream reference
if it is added to track the local memberships.

Signed-off-by: Rajesh Girada <rgirada@vmware.com>