pimd: PIM not sending register packets after changing from non DR to DR

pimd: PIM not sending register packets after changing from non DR to DR

When the router is non dr for an interface, it installs mroute to drop
the packets from directly connected source. This was done to avoid packets
coming to cpu as nocache hit. Later when it gets change from non-DR to DR,
these entries are not cleared. So the packets are still dropped.
This causes register packets not getting generated.
So cleaning up the mroute entries and channel oil without
upstream reference which was created to drop.

Co-authored-by: Saravanan K <saravanank@vmware.com>
Signed-off-by: Sai Gomathi N <nsaigomathi@vmware.com>