pimd : memory leak in rp_table cleanup.

pimd : memory leak in rp_table cleanup.

Problem Statement:
==================
valgrind shows memleaks in rp_table, when pimd shuts down gracefully.
2020-05-05 22:09:29,451 ERROR: Memory leaks in router [r4] for daemon [pimd]
2020-05-05 22:09:29,451 ERROR: Memory leaks in router [r4] for daemon [zebra]
2020-05-05 22:09:29,637 ERROR: Found memory leak in module pimd
2020-05-05 22:09:29,638 ERROR: ==6178== 184 (56 direct, 128 indirect) bytes in 1 blocks are definitely lost in loss record 21 of 21
2020-05-05 22:09:29,638 ERROR: ==6178== at 0x4C2FFAC: calloc (vg_replace_malloc.c:762)
2020-05-05 22:09:29,638 ERROR: ==6178== by 0x4E855EE: qcalloc (memory.c:111)
2020-05-05 22:09:29,638 ERROR: ==6178== by 0x4EAA43C: route_table_init_with_delegate (table.c:52)
2020-05-05 22:09:29,638 ERROR: ==6178== by 0x1281A1: pim_rp_init (pim_rp.c:114)
2020-05-05 22:09:29,638 ERROR: ==6178== by 0x11D0F8: pim_instance_init (pim_instance.c:117)
2020-05-05 22:09:29,638 ERROR: ==6178== by 0x11D0F8: pim_vrf_new (pim_instance.c:150)
2020-05-05 22:09:29,638 ERROR: ==6178== by 0x4EB1BEC: vrf_get (vrf.c:209)
2020-05-05 22:09:29,638 ERROR: ==6178== by 0x4EB2B2F: vrf_init (vrf.c:493)
2020-05-05 22:09:29,638 ERROR: ==6178== by 0x11D227: pim_vrf_init (pim_instance.c:217)
2020-05-05 22:09:29,638 ERROR: ==6178== by 0x11BBAB: main (pim_main.c:121)

Fix:
====
rp_info is allocated in pim_rp_init API. rp_info pointer is present
in rp_list and rp_table. In rp_list cleanup, the memory for rp_info
gets freed. rp_table clean up should be done first and then rp_list.

Signed-off-by: Mobashshera Rasool <mrasool@vmware.com>
(cherry picked from commit 906640dbafee986a5ac49d1089e49ac97770096f)