Fixed accessing network-input-parameters.

Fixed accessing network-input-parameters.

network topology operation assign sub DG access network-input-parameters
as network-parameters which is not defined under network-request-input
container in GENERIC-RESOURCE-API yang, modified network-topology-
operation-assign.json as below
Before: network-topology-operation-input.network-request-input.
network-parameters
After: network-topology-operation-input.network-request-input.network
-input-parameters.
jira.onap.org/browse/SDNC-87

Issue-Id: SDNC-87
Change-Id: Idd4005fb24365fef990284569dd23685590515b3
Signed-off-by: shashikanth.vh <shashikanth.vh@huawei.com>
Former-commit-id: 89ac5158f33c5358d1a943a482f139e879dbd0a9