ospfd: "ip ospf area" command can select wrong process

ospfd: "ip ospf area" command can select wrong process

Found that in some circumstances, when the "ip ospf area"
command was entered for the default vrf, the wrong ospf
process would be used to check for the presence of a
"network" statement, causing the "ip ospf area" command to
be rejected. This was due to the command using the ospf
instance lookup to find the right ospf process, which can
be in error depending on when the processes were created.

Signed-off-by: Don Slice <dslice@nvidia.com>