pimd: Allow SSM groups to co-exist with ASM groups.

pimd: Allow SSM groups to co-exist with ASM groups.

SSM groups (232/8 or user configured SSM range) can exist in the same
multicast network as ASM groups. For such groups all RPT related state
machine operations have to be skipped as defined by section 4.8 of
RFC4601 -
1. Source registration is skipped for SSM groups. For SSM groups mroute
is setup on the FHR when a new multicast flow is rxed; however source
registration (i.e. pimreg join) is skipped. This will let the ASIC black
hole the traffic till a valid OIL is added to the mroute.
2. (*,G) IGMP registrations are ignored for SSM groups.

Sample output:
=============
fhr#  sh ip pim group-type
SSM group range : 232.0.0.0/8
fhr#  sh ip pim group-type 232.1.1.1
Group type: SSM
fhr#  sh ip pim group-type 239.1.1.1
Group type: ASM
fhr#

Sample config:
=============
fhr(config)# ip pim ssm prefix-list ssm-ranges
fhr(config)#

Signed-off-by: Anuradha Karuppiah <anuradhak@cumulusnetworks.com>
Reviewed-by: Donald Sharp <sharpd@cumulusnetworks.com>
Ticket: CM-15344
Testing Done:
1. SSM/ASM source-registration/igmp-joins.
2. On the fly multicast group type changes.
3. pim-smoke.