pimd: display reg-state and join-state info in the pim_upstream output

pimd: display reg-state and join-state info in the pim_upstream output

Changed the state field in the "sh ip pim upstream" output to include
register and join state info as a comma separated value. Register info
is supressed if reg-state=NoInfo.

Sample output:
=============
root@fhr:/home/cumulus# net show pim upstream
Iif       Source          Group           State       Uptime   JoinTimer
RSTimer   KATimer   RefCnt
swp1      33.1.1.1        239.1.1.2       J,RegP      00:00:18 --:--:--
00:00:44  00:03:24       2
root@fhr:/home/cumulus#

root@rp:/home/cumulus# net show pim upstream
Iif       Source          Group           State       Uptime   JoinTimer
RSTimer   KATimer   RefCnt
lo        *               239.1.1.2       J           00:02:08 00:00:52
--:--:--  --:--:--       1
swp1      33.1.1.1        239.1.1.2       J           00:00:16 00:00:11
--:--:--  00:03:26       1
root@rp:/home/cumulus#

Signed-off-by: Anuradha Karuppiah <anuradhak@cumulusnetworks.com>
Reviewed-by: Donald Sharp <sharpd@cumulusnetworks.com>
Ticket: CM-14700
Testing Done: pim-smoke