pimd: Don't start KAT timer when traffic received on PIM disabled interface

pimd: Don't start KAT timer when traffic received on PIM disabled interface

Topology:
RP---FHR---Source

Problem Statement:
1. In FHR, Enable PIM and IGMP on source connected interface
2. Start multicast traffic. (s,g) mroute and upstream will be created as expected.
3. Disable PIM on source connected interface.
4. Disable IGMP on source connected interface.
5. Stop the traffic.

Mroute will never get timeout.

Root Cause:
In FHR, when PIMD receive multicast data packet on
source connected interface which is IGMP enabled, but PIM
not enabled. PIMD process the packet, install the
mroute and start the KAT timer.

Fix:
Don't process multicast data packet received on PIM disabled

Signed-off-by: Sarita Patra <saritap@vmware.com>