table: fix crash in LPM IPv6

table: fix crash in LPM IPv6

Unit test table_autotest results in segmentation fault.
Crash occurs in test_table_lpm_ipv6_combined().

Variable 'nht_pos0' used as array subscript is not initialized
in rte_table_lpm_ipv6_entry_add(). It will not be assigned,
if a rule does not exist.

In such case a junk number or invalid array index might result in
segmentation fault due to array out of bounds when
lpm->nht_users is used with such invalid array index.

Fix is to initialize the variables used for array subscript.

Bugzilla ID: 285
Fixes: d89a5bce1d ("lpm6: extend next hop field")
Cc: stable@dpdk.org
Signed-off-by: Jananee Parthasarathy <jananeex.m.parthasarathy@intel.com>
Tested-by: David Marchand <david.marchand@redhat.com>
Acked-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>