Description of problem:
gen_conf: Fix ECMP route

Version-Release number of selected component (if applicable):
nmstatectl 2.2.12

How reproducible:
100%

Steps to Reproduce:
$ cat << EOF | nmstatectl gc /dev/stdin
interfaces:
- name: eth0
  type: ethernet
  ipv4:
    address:
    - ip: 192.168.100.100
      prefix-length: 24
    dhcp: false
    enabled: true
routes:
  config:
  - destination: 0.0.0.0/0
    metric: 150
    next-hop-address: 192.168.100.1
    next-hop-interface: eth0
    table-id: 254
    weight: 20
EOF
NetworkManager:
- - eth0.nmconnection
  - |
    [connection]
    autoconnect=true
    autoconnect-slaves=-1
    id=eth0
    interface-name=eth0
    type=802-3-ethernet
    uuid=dfd202f5-562f-5f07-8f2a-a7717756fb70

    [ipv4]
    address0=192.168.100.100/24
    method=manual
    route0=0.0.0.0/0,192.168.100.1,150
    route0_options=table=254

    [ipv6]
    method=disabled

Actual results:
route0_options=table=254

Expected results:
route0_options=table=254,weight=20

Additional info:
https://github.com/nmstate/nmstate/pull/2390