pimd: Always create upstream reference when adding channel oil

pimd: Always create upstream reference when adding channel oil

Modify the code to create an upstream reference whenever the code
creates an channel_oil via the pim_mroute.c code.  This code also
starts a keep alive timer to clean up the reference if we do
nothing with it after the normal time.

I've left alone the source->channel_oil creation because these
are kept and tracked independently already.

Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>