[DPB] fix optional fields for child ports in scope DPB

[dmytroxshevchuk]

As part of PR:
sonic-net/sonic-buildimage#6660

What I did

After DPB cli command, optional fields 'fec' has N/A state
Before DPB:

  Interface            Lanes    Speed    MTU    FEC        Alias    Vlan    Oper    Admin             Type    Asym PFC
-----------  ---------------  -------  -----  -----  -----------  ------  ------  -------  ---------------  ----------
 Ethernet32      32,33,34,35     100G   9100     rs   Ethernet32  routed      up       up  QSFP28 or later         N/A

After DPB:

  Interface            Lanes    Speed    MTU    FEC        Alias    Vlan    Oper    Admin             Type    Asym PFC
-----------  ---------------  -------  -----  -----  -----------  ------  ------  -------  ---------------  ----------
 Ethernet32            32,33      50G   9100    N/A   Ethernet32  routed    down       up  QSFP28 or later         N/A
 Ethernet34            34,35      50G   9100    N/A   Ethernet34  routed    down       up              N/A         N/A

Expect that, fields from parent ports must be produced in child ports.

How I did it

How to verify it

Execute: sudo config interface breakout Ethernet0 2x50G -f

Previous command output (if the output of a command-line utility has changed)

New command output (if the output of a command-line utility has changed)

[allas-nvidia]

Can someone take a look, please?
Thanks

[zhenggen-xu]

Redesign needed for sonic-net/sonic-buildimage#6660